Textbook of Radiological Safety.pdf

TEXTBOOK OFRADIOLOGICAL SAFETY TEXTBOOK OF RADIOLOGICAL SAFETY K Thayalan PhD Professor and Head Radiological Physics Department Barnard Institute of Radiology and Oncology Government General Hospital and Madras Medical College Chennai, India ® JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD Chennai • St Louis (USA) • Panama City (Panama) • London (UK) • New Delhi • Ahmedabad • Bengaluru • Hyderabad • Kochi • Kolkata • Lucknow • Mumbai • Nagpur Published by Jitendar P Vij Jaypee Brothers Medical Publishers (P) Ltd Corporate Office 4838/24 Ansari Road, Daryaganj, New Delhi - 110002, India, Phone: +91-11-43574357, Fax: +91-11-43574314 Registered Office B-3 EMCA House, 23/23B Ansari Road, Daryaganj, New Delhi - 110 002, India Phones: +91-11-23272143, +91-11-23272703, +91-11-23282021 +91-11-23245672, Rel: +91-11-32558559, Fax: +91-11-23276490, +91-11-23245683 e-mail: [email protected], Website: www.jaypeebrothers.com Offices in India • Ahmedabad, Phone: Rel: +91-79-32988717, e-mail: [email protected] • Bengaluru, Phone: Rel: +91-80-32714073, e-mail: [email protected] • Chennai, Phone: Rel: +91-44-32972089, e-mail: [email protected] • Hyderabad, Phone: Rel:+91-40-32940929, e-mail: [email protected] • Kochi, Phone: +91-484-2395740, e-mail: [email protected] • Kolkata, Phone: +91-33-22276415, e-mail: [email protected] • Lucknow, Phone: +91-522-3040554, e-mail: [email protected] • Mumbai, Phone: Rel: +91-22-32926896, e-mail: [email protected] • Nagpur, Phone: Rel: +91-712-3245220, e-mail: [email protected] Overseas Offices • North America Office, USA, Ph: 001-636-6279734, e-mail: [email protected], [email protected] • Central America Office, Panama City, Panama, Ph: 001-507-317-0160, e-mail: [email protected] Website: www.jphmedical.com • Europe Office, UK, Ph: +44 (0) 2031708910, e-mail: [email protected]; [email protected]; [email protected] Textbook of Radiological Safety © 2010, Jaypee Brothers Medical Publishers (P) Ltd. All rights reserved. No part of this publication should be reproduced, stored in a retrieval system, or transmitted in any form or by any means: electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the author and the publisher. This book has been published in good faith that the material provided by author is original. Every effort is made to ensure accuracy of material, but the publisher, printer and author will not be held responsible for any inadvertent error (s). In case of any dispute, all legal matters are to be settled under Delhi jurisdiction only. First Edition: 2010 ISBN 978-81-8448-886-9 Typeset at JPBMP typesetting unit Printed at Ajanta Offset Dedicated to My Parents (Late) Thiru K Kuppusamy Jayamkondar Thirumathi K Arukkani New Delhi . AROI . AIIMS Ex President. The chapters are concise and complete in all aspects. There was a long-felt necessity for such a textbook. DRBRAIRCH. Dr B R Ambedkar Institute Rotary Cancer Hospital All India Institute of Medical Sciences Ansari Nagar. I wish Dr Thalayan all success in his maiden venture. The chapter on "Regulations and Dose Limits" is of particular relevance as it contains details of regulatory aspects. Department of Radiation Oncology Chief. The author must be complemented for the lucid style of writing. AROI Foreword It brings me immense pleasure to write the foreword for this book which is focusing on radiation protection. Prof GK Rath MD Professor and Head. Large numbers of illustrations have been included to explain the subject matter. It contains all the essential aspects of radiological safety. Nuclear Medicine. The book will go a long way in helping the Radiation Oncology.com Dr GK Rath MD Professor and Head. Dr Thalayan has an extensive experience in the field of Medical Physics and this book sums up his vast experience for the benefit of the readers. Radiology and Medical Physics Community and will be very useful for the health care providers at all levels in these specialties. 26594798 Fax: 91-11-26589821 E-mail: gkrath@rediffmail. Bibliographies at the end of each chapter have been included to serve as additional reading material on the subject. AIIMS Ex President.110 029 Tel (Off): 91-11-26594864. DRBRAIRCH. Department of Radiation Oncology Chief. . on radiological safety. NCRP and AERB. waste disposal. regulation. The whole objective is to remove misconception about radiation and prepare the minds of younger generation to face the future challenge confidently. I also acknowledge the assistance offered by the Dr Kamakshi Memorial Hospital staff. diagnostic radiology. a unique textbook. I am very much thankful to my family members for their support and cooperation. it is important that every one should be aware of the safety concepts. As such. by whom I got inspiration and passion towards teaching. Radiation is analogous to fire which has both beneficial and harmful effects. planning of the installation. biological effects. with practical examples and illustrations. no single document is available for the above purposes. nuclear medicine and radiotherapy. in the form of a book.. This book is intended for postgraduates of medical physics. An attempt has been made to bring all the relevant information including safety terminology. transport. quality assurance. covering the entire fields of radiology i. carry out quality assurance and radiation survey without much cumbersome and perform the day-to-day medical physicist’s job with ease and involvement. etc. This book may also find a place for the preparation of RSO examinations for medical physicists. I invite the readers to offer constructive comments for the future improvement of the book. and the information is collected from safety codes and guides of international and national agencies like IAEA. an attempt has been made to bring quantitative data from international reports and recommendations. I also thank Mrs G Shakunthala for neatly typing the manuscript. Hence. to establish a safe work culture while handling radiation sources in the hospital. dose limits. personnel safety. diagnostic radiology. Large numbers of tables and figures are incorporated wherever necessary for better understanding of the reader. waste disposal and radiation emergency. K Thayalan . especially the medical physics colleagues. exposure control. etc. Preface It gives me immense pleasure to come out with a textbook on radiological safety. The inherent philosophy is to minimize the hazards and maximize the benefits in order to bring down radiation doses within the regulatory control limits by which we can ensure the safety of the occupational workers as well as the patient and public.. in the preparation of the text. nuclear medicine and radiotherapy. monitoring. Moreover. wherever necessary. It is my long-felt dream to have a complete book. I also acknowledge my teachers.e. This may enable the new entrants to plan a radiation facility. regulation. . .................................................... 14 Cell 14 Interaction of radiation with tissue 14 Linear energy transfer 16 Biologic effects 17 Radiation effects on DNA 22 Radiation effects in utero 23 Radiation risk 24 Ten day rule and its present status 29 3. 64 General guidelines 64 Establishing a diagnostic X-ray facility 65 General radiography installation 68 Fluoroscopy installation 68 Mammography installation 69 Computed tomography installation 70 Establishing a nuclear medicine facility 71 In-vivo diagnostic facility 74 In-vitro and radioimmunoassay (RIA) 75 ........................................... 31 Time 31 Distance 32 Shielding 34 Half value layer 35 Sources of exposure 37 Leakage limits 39 Protective barrier design 40 Facility design for diagnostic X-rays 42 Facility design for nuclear medicine 47 Facility design for radiotherapy 48 4........................................................... Contents 1..... Radiation Exposure Control . Planning of Radiological Facility ......................................... Biological Effects of Radiation ... Safety Concepts ..................................................... 1 Introduction 1 Radiation units 2 Equivalent dose 4 Effective dose or effective dose equivalent 4 Committed dose 6 Collective dose 6 Genetically significant dose 7 Detriment 8 Annual limit on intake 8 ALARA 8 Sources of radiation 9 2................... ... Textbook of Radiological Safety Radionuclide therapy 78 Establishing a radiotherapy facility 79 Brachytherapy facility design 91 5.......................................................................................................................................................... 119 Introduction 119 Quality assurance for diagnostic radiology 119 Quality assurance for radiography unit 120 QA for mammography X-ray unit 133 QA for fluoroscopy X-ray unit 134 Quality assurance for computed tomography 134 Quality assurance for nuclear medicine 137 QA for gamma camera 138 QA for single photon emission computed tomography (SPECT) 140 Quality assurance for PET-CT 141 Image quality tests 146 QA for radiopharmaceuticals 147 Quality assurance for radiotherapy 154 QA for linear accelerator 154 QA for HDR brachytherapy 159 7........... Radiation Monitoring ... Regulations and Dose Limits ................... Quality Assurance ....................... 167 Atomic energy act-1962 167 Atomic energy regulatory board 167 Radiation protection rules-2004 168 Regulatory controls for diagnostic X-ray equipment and installations 181 Regulatory controls for nuclear medicine facilities 184 Regulatory control for radiotherapy equipment and installations 190 8.. 95 Personnel monitoring 95 Film badge 96 Thermoluminescent dosimeter 97 Pocket dosimeter 100 Personnel monitoring systems and features 102 Area monitoring 103 Radiation survey in diagnostic radiology 107 Radiation survey in nuclear medicine 111 Radiation survey in radiotherapy 112 Calibration and maintenance of radiation monitoring instruments 117 6....................................... Personnel Protection ............................... 204 Radiography 204 Protection in fluoroscopy 212 Protection in computed tomography 214 Protection in pediatric imaging 215 Pregnancy and radiation 221 Protection in nuclear imaging 227 Protection in radionuclide therapy 232 xii Pregnancy and radiation protection in nuclear medicine 233 ................. ......................................... Transport of Radioactive Materials ...................................... transport and delivery of package 257 Consignor’s declaration 258 Tremcard 259 Information to carriers 260 10.............. 289 Type of radiation accidents 289 Diagnostic radiology-skin injuries 294 Nuclear medicine: Radiation accidents 297 Radiotherapy: Radiation emergencies 300 Brachytherapy: Radiation accidents 308 Emergency preparedness: Actions 309 Medical management of personnel exposed to radiation 313 Index ................ Radioactive Waste Disposal ............... 267 Introduction 267 Waste management 267 Sources and nature of waste 268 Classification of waste 269 Types of radioactive waste 270 Disposal of low activity wastes into the environment 276 Disposal of radioactive effluent into the ground 276 Disposal of P-32 and I-131 into municipal sewers by medical users 277 Disposal of radioactive waste from nuclear medicine procedures 278 Routine protective clothing 280 Decontamination procedures 281 11........................................... storage......................................... Contents Radioiodine therapy and pregnancy 235 Staff protection 237 Personnel safety during source transfer operations of teletherapy and HDR brachytherapy units 238 Pregnancy and radiation protection in radiotherapy 240 Records 243 9. 245 Introduction 245 Types of packages 246 Transport index 248 Packaging and package requirements 249 Preparation of the package for transport 253 Marking of the package 253 Labeling of the package 254 Placards 256 Booking....... Radiation Emergencies .................................... 319 xiii ................................................ analogous to fire. Roentgen on November 15. In 1915. Radiation was used in medicine immediately after the discovery of X-rays by W. presently the Barnard institute of Radiology and Oncology. several cases of erythema. It was made as an International Committee in 1928 and later (1950) transformed as “International Commission on Radiological Protection”(ICRP).g. for the purpose of radiological safety. the British Roentgen Society made the first radiation protection recommendations. e. Radiobiology experiments. The civilian use of X-rays in India began in 1900 at the Government General Hospital. 1895. Radiation hazards were realized in the beginning of 20th century. which possess both benefits and hazards. and (ii) particles. Atomic bomb explosion-Hiroshima and Nagasaki 4. In 1921 Ironside Bruce. . Chennai. p. Radiation is a double edged weapon. a pioneering radiologist in a London Hospital died of cancer at the age of 38. which was formed in 1946. In 1902 the first X-ray induced skin cancer was reported. e. That cargo had the first X-ray tube used in India. Chapter 1 Safety Concepts INTRODUCTION Radiation is small pockets of energy. Radiation hazards were witnessed by the following events in early days: 1. Within 6 months of their use. There are two types of radiation namely: (i) photons. The ICRP is the first standard setting body formed. The Indian army employed hefty porters to carry the cargo. Watch dial painters-switzerland 3. Uranium mine workers 2.γ.(100 bounds) on a pole for 200 miles in the Hyber pass region (Pakistan). X. dermatitis and alopecia were reported among X-ray operators and their patients. It was used in India in 1898 within 3 years of its discovery. The similar organization at the USA is the National council on radiation protection and measurements (NCRP). n and α. To regulate the safe use of radiation the “British X-ray and Radium protection committee” was formed (1921). Major Bewoor used it effectively in the North-West frontiers. which travels as waves and transfer energy from one point to another point. The X-rays were used indiscriminately in the early years and have caused visible damage to several physicians and X-ray enthusiasts.g.C. Similarly several lives were lost due to excessive X-ray exposures. e. 2 . The unit of absorbed dose is rad (r). that take place in the medium. 1Gy = 1 J / kg The unit rad is related to gray as 1Gy = 100 rads. the uncharged particles (photons and neutrons) transfer kinetic energy to the charged particles (e and P). When radiation interacts with matter.58 × 10-4 C / kg of air There are some difficulties in the unit of roentgen. The unit may also be defined in terms of SI unit as 1R = 2. It can be used only up to a photon energy of 3 MeV. The SI unit of absorbed dose is Gray (Gy). The SI unit is Gray and the special unit is rad. in a small volume around a point.s. Exposure is a source related term. Kerma (K) is the measure of kinetic energy transferred to the charged particles. produces in air. The unit of exposure is roentgen (R).001293 grams of air (1cc of dry air at NTP). It is not a unit of dose. RADIATION UNITS Exposure – Roentgen The term exposure (X) refers the radiation quantity measured in terms of ionization in air. Kerma Kerma stands for kinetic energy released in the medium. It is defined as the sum of the initial kinetic energy of all the charged ionizing particles.u. The unit for kerma is Joul per kilogram (J/ kg). which means radiation absorbed dose. Absorbed Dose—Rad / Gray The term absorbed dose (D) refers the amount of energy absorbed per unit mass of the substance. 1 rad =100 ergs/gram. It is defined only for x and gamma radiation in air. Exposure from an X-ray source obeys inverse square law. ions carrying 1 e. Textbook of Radiological Safety These bodies issue periodical reports on radiation safety aspects of various application of ionizing radiation. which describes the initial interaction of the photon with an atom. One roentgen shall be the quantity of x or gamma radiation such that the associated corpuscular emission per 0. which is a measure of absorbed energy. This unit is independent of type of radiation and the medium. of quantity of electricity of either sign. liberated by photons in a material of unit mass. These concepts are explained in the following paragraphs and chapters. Safety Concepts Exposure Rate Constant It is defined as the exposure per hour from 1 mCi point source at a distance of 1cm and it is expressed in R-cm2/mCi-h. hence 1RMM = (1/0.326. It is defined as the exposure per minute from 1 Ci point source at a distance of 1m and it is expressed in R-m2/Ci- min.1: RHM and RMM of different radioisotopes Radioisotope RHM RMM Activity (Ci) equivalent to 1 RMM Radium-226 0. then it is called RHM (Roentgen Hour Meter).7 × 1010.825 0. Mostly RHM is employed for calibration purposes in Brachytherapy and industrial radiography. RMM and CURIE The unit of activity is curie and it is defined as the number of disintegration per second from 1 gram of radium and it is found to be 3.0137 72. cesium and iridium radioisotopes are 13. 0.307/60 = 0.0217. RMM is the most preferred and useful terminology in teletherapy source calibration. the exposure rate constant of cobalt.69 respectively.99 Cobalt-60 1. 0. It is defined as the exposure per hour from 1Ci point source at a distance of 1m and it is expressed in R-m2/Ci-h. the corresponding RMM value is 1.26 and 4.0078 128.20 Example 1: If a Cobalt teletherapy source is purchased with 200 RMM capacity.0217)= 46. Table 1.326 0.0054 185. In the case of cobalt.08 × 200 = 9216.469 respectively. cesium and iridium radioisotopes are 1. For example. For example.0217 RMM corresponds to 1Ci.307. and 0.58 Ci 3 .307. Hence the RHM of cobalt. Similarly.07. what is the corresponding activity of the source in Ci? 1 RMM = 46.469 0.18 Iridium-192 0. In practice RHM of a given radioisotope can be obtained by dividing the exposure rate constant by a factor 10.0217 46.1). it can be applied to different radioisotopes (Table 1. RHM and RMM If the exposure rate constant is defined for 1Ci source at 1m.08 Ci. Instead of hour one can also express it for one minute. 3. if the RHM of the cobalt radioisotope is 1.08 Cesium-137 0.307 0.08 Ci 200 RMM = 46. then it is called RMM (Roentgen Minute Meter). 2 gives the suitable weighting factors for various type of radiations. EQUIVALENT DOSE The biological effects of radiation depend not only on absorbed dose (D) but also on the type of radiation. what is the corresponding RMM value? 46. which describes the dose to the whole body and is derived from 4 equivalent dose. the radiation induced effects vary with the sensitivity of the organ. This is discontinued now and replaced with equivalent dose. Also 1 Sv=100 Rem (Radiation equivalent men). the ICRP report 26 (1977) introduced the dosimetric quantity Equivalent dose (HT). where Rem is the special unit of equivalent dose. which is an average dose and not a point dose. It is the absorbed dose averaged over a tissue or organ and weighted for the radiation quality that is of interest. milli sievert (mSv) unit is used. Textbook of Radiological Safety Example 2: If a Cobalt teletherapy source is purchased with 10.<10keV 5 Protons 5 Neutrons.2MeV-20MeV 10 Electrons 1 Neutrons >20MeV 5 Neutrons. Earlier the term quality factor (Q) was used to evolve dose equivalent (absorbed dose × quality factor). 1 Sv = 1000 mSv 1 mSv = 100 mRem. In practice. Table 1. and is given as HT=D × WR Where WR is the weighting factor for the radiation type and it is analogous to RBE in radiobiology. Hence.000 Ci = (1/46. Swedish Radiologist) is the SI unit of equivalent dose and one Sievert (Sv) =1 Joule/kilogram.08 Ci = 1RMM 10.2: Radiation weighting factors (WR) Radiation type WR Radiation type WR Photons (all energies) 1 Neutrons. Hence. To account these non uniform irradiation and organ sensitivity variation. It is defined as .000 = 217 RMM. the ICRP-26 introduced the term effective dose (E).000 Ci capacity. Table: 1.08) × 10. EFFECTIVE DOSE OR EFFECTIVE DOSE EQUIVALENT The whole body exposures are not uniform and dose equivalents for various tissues may differ markedly.100keV-2MeV 20 Sievert (Rolf Sievert.10keV-100keV 10 Alpha particles 20 Neutrons. liver. kidneys 0.01 Bone surfaces 0. skin 0.60 mSv(ICRP 60) = (21 × 0.3 × 0.12+2. brain.5 × 0. Safety Concepts E = ΣWT × HT where WT is the weighting factor for the tissue T. liver.01 Remainder 0. lung and stomach 0.12+ 23.3 × 0. the radiosensitivity of the breast tissue and gonads are reassessed by the ICRP (2005) and the revised weighting factors are given the table. Organ of higher sensitivity carries a higher risk for a given dose.12+2. Calculate the effective dose with both old and revised tissue weighting factors. It is seen that testes and ovaries are the most radiosensitive tissues as they have the highest value of weighting factor as per ICRP 60.17 × 0.02 Salivary glands. The Table 1. compared to the total risk of inducing stochastic effects if the same radiation dose is received by the whole body.05 Breast.05 Gonads.17 and 2. 5. stomach 0.5 × 0. Table: 1.07 mSv (ICRP2005) The revised tissue weighting factors predicts 32 % higher risk for a given radiation dose. The weighting factor of a particular tissue or organ is the risk of stochastic effects being induced in the organ when singly irradiated.5.05 Remainder 0.05 Thyroid.12+5.12 Red bone marrow 0.05) = 6. The sum of the weighting factors is unity.12 Bladder. It is used to evaluate the probability of stochastic effects at low doses.3: Tissue weighting factors (WT) Tissue WT Tissue WT (ICRP 60) (ICRP 2005) Testes and ovaries(Gonads) 0. esophagus 0.12+5.05+ 23.20 Bone marrow. HT is the mean equivalent dose received by the tissue and E is the summed organ or tissue doses as an overall whole body dose. The effective dose: E = ΣWT × HT = (21 × 0. urinary bladder 0. thyroid 0. The unit of effective dose is Sievert (Sv).3 gives the tissue weighting factors for various tissues. lung. 5 .05) = 4. This quantity expresses the overall measure of health detriment associated with each irradiated tissue or organ as a whole body dose and considers the radiosensitivity of each irradiated organ or tissue. breast 0. lung.30 mSv respectively.05 Bone surface.12 Colon. esophagus 0. However.12 Colon. bone marrow and thyroid receive dose of 21. 23.17 × 0.10 Example 3: In a CT scan study the tissues breast. and T1/2 eff = 2 hours. over a period of time t. It is defined HT(t) = HT × t where t is the period of time in years. It is related to the physical half life (T1/2 phys ) and biological half life (T1/2 biol) as follows: 1 1 1 = + T1/2 eff T1/2 phys T1/2 biol One can not alter the physical half life. It is defined as the dose equivalent accumulated over a period of 50 years following the intake of radioactive material.(vi) proximity of other organs and (vii) weighting factor of the organ. E(t) = ΣHT(t) × WT The other factors which influences the dose equivalent are. the individual dose may be multiplied by the population number exposed and it is called the collective dose. Whereas the biological half life can be reduced by increasing the rate of excretion of the radionuclide from the body. which is a character of a given radionuclide. (iv) radiation weighting factor. (v) size and shape of the organ. It is the absorbed dose the individual receives as a result of the intake of radioactive material. If the committed organ or tissue equivalent dose is multiplied by the suitable tissue weighting factors then the sum of the products is called committed effective dose (E(t)). The individual will continue to receive a dose of radiation as long as the traces of radioactivity remain with in the body. COLLECTIVE DOSE To assess the overall effect of radiation dose on a large group of people. then 1/ T1/2 eff = (1/6) + (1/ 3). (iii) decay system. Textbook of Radiological Safety COMMITTED DOSE If an individual is subjected to a radiation burden over a period of time. For example. (i) the concentration of the activity in the organ. then committed dose is the term to be used. a radio nuclide has a physical half-life of 6 hours and a biological half-life of 3 hours.(ii) whether the concentration is uniform or localized. The effective half-life is always less than either the physical or biological half-life The committed dose equivalent is the quantitative assessment of the effect of a particular intake of radioactivity over the whole of a individual’s working life. If N is the number of population receiving a mean organ equivalent dose HT . In the case of children the period is taken as 70 years. The factor which determines the remaining activity in the body is the effective half life (T1/2 eff ). then the collective equivalent dose (ST) is given by 6 . In general the CEDE is decreasing in medicine due to small size of the exposed population and improved health physics practices. It means that the occupational workers getting an additional 63% (2000/3200) over the natural background. if a population of 10 million people are exposed to a background dose of 3 mSv. can be used as a method to assess the impact of human health from population radiation exposures and it is expressed in person-Sv.4 Table 1. GENETICALLY SIGNIFICANT DOSE The genetically significant dose (GSD) is defined as that equivalent dose that. then the collective effective dose is 30. Safety Concepts ST = Σ HT(t) × N Collective Effective Dose Equivalent In a similar way the collective effective dose (S) can be defined. for all occupations.4: Annual collective effective dose equivalents for workers in various occupations in USA Occupation Annual collective effective dose equivalents (person-Sv) Nuclear power operation 550 Medicine 420 Industry 390 Airline crews and attendants 170 Uranium miners 110 The uranium miners CEDE is small due to relatively small size of the workforce involved in the occupation. It is the whole body exposure to a population group exposed to radioactive materials in the environment and can cover successive generations of the populations being studied. It is 7 . S = E(t) × N In a country.000 man- Sv. Whereas the annual CEDE attributable to natural background radiation for the same population is about 3200 person-Sv. The CEDE values for different occupations are given in Table 1. The total annual CEDE for all occupationally exposed workers is about 2000 Person–Sv. It is expressed in Sievert (Sv). would be expected to produce the same genetic injury to the population as do the actual doses received by the irradiated individuals. if received by every member of the population. The collective effective dose equivalent (CEDE). 28 mSv (22%) from technological sources (NCRP-report 93. Health detriment is an estimate of the risk of reducing in length and quality of life occurring in a population following exposure to ionizing radiations.20 mSv (15%). the major contributor is diagnostic X-rays. ANNUAL LIMIT ON INTAKE The Annual limit on intake (ALI) is the that quantity of radionuclide which. but also the severity of the effect. especially in medicine. For example. Annual GSD from all radiation sources is about 1. probability of death and reduction of life expectancy) are considered to arrive the mean health detriment.3 mSv that includes 1. It assumes a linear dose effect relationship. If the same dose was received by every member of the population. Textbook of Radiological Safety used to assess the genetic risk or detriment to the whole population from radiation exposure. 0. The higher proportion of female component is due to the location of the ovaries within the pelvis. taking into account not only the probability of each type of deleterious effect. Among the technological sources. ALARA As Low As Reasonably Achievable (ALARA) term was introduced by ICRP- 26. Usually several parameters (e. DETRIMENT Detriment is a measure of harm caused by exposure to radiation. It states that doses to patients and staff should be kept as low as reasonably achievable. 8 . would lead to a committed effective dose equal to the occupational annual limit on effective dose. taken into the body during 1 year. Every reasonable effort must be made to reduce radiation levels below the stated dose limits within economic and social limits. the patients undergo X-ray examinations may receive a dose of about 10. It is the expectation of harm incurred from an exposure to radiation. which places them in the primary beam during most abdomino pelvic examinations.0 mGy. The genetically significant dose (GSD) is used to assess the genetic risk or detriment to the whole population from radiation exposure.1987). In this the equivalent dose to the gonads of each exposed individual is weighted for the number of progeny expected for a person of that sex and age. one- third is attributable to male and two-third to females.g. it would be expected to produce the same total genetic effect on the population.02 mSv (78%) from natural background and 0. Among the 15 %. The GSD accounts the child bearing potential of the patient population. and ingestion.(ii) Terrestrial (Primordial) radionuclides. A 5 hr transcontinental jet aircraft travel result in 25 μSv equivalent dose.g. Primary cosmic rays. Natural Radiation Source The natural radiation sources includes (i) Cosmic rays. and hence the indoor effective dose is 20% lesser than outdoor. The annual average per capita total effective dose equivalent is 3. e. Safety Concepts SOURCES OF RADIATION The sources of radiation are classified into (i) Natural radiation sources. Background radiation involves both natural and man made low level radiation exposure to all members of the public. It is estimated that at 30.6 mSv) arise from technologic enhancements of naturally occurring sources and artificial radiation sources (diagnostic X-ray is the major contributor). and (iii) Internal Radioisotopes.US data). It is greater at the earth poles than the equator. in which protons accounts for 80%. muons) and electromagnetic radiations. A part of secondary cosmic ray particles collide with stable atmospheric nuclei and produces cosmogenic radionuclides. (ii) Enhanced natural sources. Their physical half lives are comparable to the age of the earth (4. Air crews and frequent fliers receive an additional annual equivalent dose of 1mSv. Air travel increases individual’s cosmic ray exposures.6 mSv (NCRP-93. that includes primary and secondary. Apollo astronauts received an average equivalent dose of 2.75 mSv during the lunar mission.000 ft altitude the equivalent dose is about 5 mSv per hour and it is doubling in every 1500 feet. Their decay products are the major contributors of terrestrial radiations. Cosmic Rays Cosmic rays are extraterrestrial radiation that strikes the earth’s atmosphere. inhalation. Structures provide some protection against cosmic rays. but their contribution to natural background is very little. The primary cosmic rays collide with atmosphere.5 billion yeras). About 82% of the above exposure (3 mSv) arise from naturally occurring sources. which makes 8% of the natural background. 18% (0. producing showers of secondary particles (electrons. This will vary with region and Kerala and Brazil have high background levels of radiation (100 mSv/year). Terrestrial Radiations Terrestrial radionuclides that have been present on earth since its formation are called primordial radionuclides. They mainly contribute in the form of external exposure. Cosmic exposures increase with altitudes. (iii) Artificial radiation sources (man made) and (iv) Occupational exposures. 9 .p) 14 6 C. The average per capita equivalent dose is 270 μSv per year.147 N (n. thorium decay products and K-40). It is deposited in the tracheobronchial region of the lung. and Th-232 are mainly responsible for external exposure and they account an equivalent dose of 280 μSv per year. which are present the in the human body. Radon inhalation accounts an equivalent dose of 2 mSv/year to the bronchial epithelium. It accounts for about 55% of natural background. This may vary depending upon the local concentration of terrestrial radionuclides. granite which may contribute an annual effective dose of 30 μSv /year. optical lenses (uranium) contribute <1% annual effective dose Artificial Sources The artificial sources of radiation includes medical exposure. Inhalation: Rn-222 (U-238) is a noble gas. Its decay products are the most significant source of inhalation exposure. It produce an effective dose equivalent of 2. Enhanced Natural Sources Enhanced natural sources mainly consists of consumer products. dental prostheses. which burdens the bronchial epithelium. Radon concentration vary widely both seasonal and diurnal. energy conservation techniques. Internal Radionuclides Internal radionuclides includes K-40 and C-14. It is a naturally occurring isotope of potassium having higher concentration at the skeletal muscle. Ingestion: Ingestion of food and water is the second largest source of natural background in which K-40 is the most significant. Weatherproofing of homes.U-238. It emanates from sail and is restricted by structures. The largest contributor is tobacco products. certain ceramics. Building materials consists of uranium. thorium and potassium and these are present in brick. The main contributor is K-40. Cumbustible fuels including coal. Textbook of Radiological Safety External exposure: K-40. natural gas and consumer products includes smoke alarms (americium-241).3 × 109 years. Mining and agricultural activity contribute to a lesser level by fertilizers (uranium. which can be easily measured and reduced.8μSv/year. decreased ventilation are resulting in higher indoor radon concentration. concrete. It accounts an average equivalent dose rate of 400 μSv/year. nuclear power and occupational exposure. decays to polonium-218 by alpha emission with half life of 3. . radioactive 10 fallout. gas lantern mantles (thorium).which emits β and γ rays and decays with a half life of 1. Radon gas dissolved in domestic water supply can contribute 10-60 μSv/ year.8 days. televisions. account for the above exposures. and to a lesser extent. Occupational Exposure The occupational exposures associates with uranium mining (12 mSv per year). Ba-140. cardiac catheterization) may exceed 15 mSv. Mn-54. aviation and research. Substances in consumer products such as tobacco. reactor operations.5. It results in an annual effective dose equivalent of <10 μSv.1 shows the % contribution of various radiation sources to the total average effective dose 11 . The most significant contributor is Carbon-14. and computer screens. However special procedures involving fluoroscopy and cini- radiology (e. nuclear power operations.5 μSv). X-ray technologist receive an average annual effective dose of 1 μSv. is obtained by dividing the annual collective effective dose equivalent by the size of the population. plutonium and transplutonium elements. It contributes about 2 % of the artificial radiation exposure. Radiologist. These are only partial body exposures (head & extremities). if lead apron is used during the procedure. the domestic water supply. 137. Ce-144. smoke detectors. mining. medical diagnosis and therapy. The occupational exposures for various categories are listed in Table 1. building materials. Both produces an annual average effective dose equivalent of 540 μSv per year. Radioactive Fallout It arises from atmospheric testing of nuclear weapons and consists of Carbon-14 (70%) and other radionuclides including H-3. The Fig. 1. The UNSCEAR and the NCRP have published the global annual dose contribution from various sources of radiations. and application of phosphate fertilizers.6. It involve all phases of fuel cycle. Safety Concepts Medical Exposure The majority of the exposure is from medical X-rays (Fluoroscopy & Computed tomography) which contribute to 58% of the artificial radiation exposure. It accounts for about 69% of artificial radiation. non uranium mining. Nuclear Fuel Cycle The contribution from nuclear power production is very minimal. Consumer Products It accounts to 16% of the artificial radiation exposure. which is presented in Table 1.g. Next contributor is the nuclear medicine which is 21%. manufacturing. The average annual effective dose equivalent to a population from all radiation sources. which is about 1% of artificial radiation (Annual effective dose is <0. Cs-136. and waste disposal. It contributes 2% of the manmade radiation exposures. 007 <0.5: Annual occupational effective dose equivalent (US Data) Category Average annual total effective dose equivalent (mSv) Uranium miners 12.5 0. lung is the organ that receives highest dose equivalent from both smokers (polonium-210) and non smokers (radon-222). 1. 1.0 Airline crews 1.3 0. Smoking is the largest contributor (45%) to the average population effective dose equivalent.1 0. The Fig. NCRP-93(1987).0 mSv/year.002 0.0005 3.39 8 0.6: Global annual radiation dose distribution from various sources of radiation Sources UNSCEAR (1993).2 highlights the % contribution of various types of manmade radiation sources.7 equivalent in the US population.2 0. Hence.1: The % contribution of various types of man-made sources to the total average effective dose equivalent to the US population .0 Nuclear power operations 6.6 mSv/year 12 Fig.1 0.3 Occupational <0.0 Radiologists 0.27 Medical 11.6 0.0 Gamma rays 17. Textbook of Radiological Safety Table 1.01 discharges <0.69 mSv/year 100 3.40 Radioactive fall out 0.3 15 0. Percentage and mSv/year Percentage and mSv/year Radon 48.0 ⎭ 0.3 0.1 0.7 X-ray and Nuclear Medicine technologists 1.07 Total 100 2.30 55% 2. excluding smoking.1 0.001 0.53 Internal 8.28 Cosmic rays 14. which is estimated as 3. Table 1.23 11 0.46 8 0.1 ⎫ ⎬ Products <0.3% 1. 3. Safety Concepts Fig.1.) Lippincott Williams & Wilkins 2002. International Commission on Radiological Protection ICRP 26 Annals of ICRP. . New Delhi 2001. Thayalan K. staff and the public. genetics. BIBLIOGRAPHY 1. Jaypee brothers Medical publishers (P) 13 LTD. Eugene RJ. Patrick AK. 2. decay patterns of radioactivity released in the environment and absorbing power of different materials to different radiation. The success of radiation protection mainly lies on the education of staff. Donald TG. Basic radiological physics. methods of reducing radiation dose.) Churchill Livingstone 2007. The essential physics of medical imaging.2: The % contribution of various components of man-made radiation sources (Source BEIR VII Report) Medical use of radiation warrant an optimal compromise between clinical utility and radiation dose to patients. 5. Pergamon press 1997. (5th edn. They should be educated on radiobiology.) Hodder Arnold. 4. Jerrold TB et al. The physics of diagnostic imaging (2nd edn. Martin V. (2nd edn. Principles of Radiological physics. David JD. UK 2006. Paul C. risk analysis. brain etc. hemopoietic system and nervous system). It makes us to understand the sequence of events (damage or repair) that occurs after the absorption of radiation energy. are called genes. cell cycle. digestive system. nature of exposure (whole body/partial body). The nucleus contains tiny thread like structures known as chromosomes. Reproductive cells contains only 23 chromosomes. Somatic cells constitute various tissues such as skin. dose rate. in turn produces moving . Many organs constitute a system (like respiratory system. All somatic cells in human body contain 46 chromosomes as 22 pairs and two sex determining chromosomes. which participate in the reproductive process. Living organisms are made up of either a single cell or many cells. fractionation. They are sperm in males and ovum in females. Cell consists of a nucleus. liver. ionization and thermal heating. Chapter 2 Biological Effects of Radiation Radiation biology is a scientific discipline which deals with the study of the action of ionizing radiation on healthy and diseased tissue. Both the cell and cytoplasm are enveloped by a membrane. which are made up of deoxyribonucleic acid (DNA) and protein. Human being is a multi-cellular organism built up of 10 14 cells. There are many variables that determine the biological response to radiation exposure. Germ cells are those. presence of radioprotectors /sensitizers and age of the exposed individual etc. which is known as cell membrane or plasma membrane. The constituents of cytoplasm control the functions of the cell. CELL Cell is the basic unit of life. These include the dose. and (ii) reproductive (or germ) cells. Cells of similar nature constitute a tissue and different tissues form an organ. Cells are mainly classified into two categories: (i) somatic cells. Sections of chromosomes. which is surrounded by a viscous liquid known as cytoplasm. INTERACTION OF RADIATION WITH TISSUE Radiation deposits energy in tissues randomly and rapidly (<10-10Sec) via excitation. The DNA molecules contain all the information required for the cellular function in coded form and thus control the nature and growth of the individual. which contain information for specific functions. These effects appear after a period of time (latent period). These interactions produce a large number of free radicals. The absorption of radiation by a water molecule (radiolysis) results in ion pairs (H2O+. cell death. For example. These electrons interact with atoms and molecules leading to chemical and molecular changes. Human body tissue is composed of 70-85% water. In direct interaction. This is known as chromosomal aberration.which are unstable and forms free radicals H* (hydrogen) and OH* (hydroxyl) as follows: H2O → H2O+ + H2O – (ion pairs) H2O+ → H+ + OH* H2O– → H*+ OH– OH* + OH* = H2O2 (hydrogen peroxide) H* + O2 = HO2* (Hydroperoxyl radical) Free radicals are extremely reactive chemical species and perform variety of reactions. with little biologic significance. free radicals are the primary agents that cause the 15 . In indirect mode. which may vary from minutes to years. The damaging effects of free radicals is enhanced with presence of oxygen. The frequency of chromosomal aberrations increases with the radiation dose and hence the magnitude of aberrations is a biological indicator of radiation dose absorbed in human body. Biological Effects of Radiation electrons. It involves rupture of cell membrane and break of chromosome structure. The X and γ rays effects in macromolecules of living system are mainly due to indirect interactions. H2O –). For example. Radiation interactions that produce biologic effects are classified as direct and indirect action. resulting in DNA strands break. Chromosomal aberration analysis (CAA) is useful in determining the radiation dose received by a person who is accidentally exposed to high radiation dose (>100 mGy). The fragments of chromosomes produced in a direct interaction. oncogenic transformation and acute radiation sickness. which are uncharged atoms or molecules with an unpaired electron and hence are highly reactive. radiation interacts with oxygen and water molecules present in the cell. In the case of low LET radiation. and the major interaction (three-fourth) is indirect action. the radiation ionize or excite the molecules such as DNA. Major portion of the radiation energy appear as heat. These changes may appear as biological effects such as chromosome breakage. They act as strong oxidizing or reducing agents by combining with macromolecules. free radicals interfere with cell functions and may inactivate cellular mechanism or break DNA bonds. can join together to form chromosomes with abnormal structures. the radiation interacts with the medium and produce radicals which in turn interact with the target molecule. RNA and protein directly. base damage can be repaired. cell transformation and chromosome aberrations and (ii) cell death. when the chromatin material is being distributed to daughter cells. All radiations are capable of producing same type of biologic effects. by specific endonucleases and exonucleases that are present. Repair mechanisms exists within cells which repair the cells and return to pre irradiated state. bone marrow cells. In other words different radiations of equal dose do not produce the same level of biologic response. 2. Fig. 2. To evaluate the effectiveness of different radiations the term Relative biological effectiveness (RBE) was introduced and it is defined as follows: Dose of 250 kVp X-rays required to produce certain effect 16 RBE = Dose of test radiation required to produce the same efffect . reproductive cells are more radiosensitive. Textbook of Radiological Safety biologic effects. Direct and indirect interactions of radiation with cell ultimately result in (i) cell modifications like gene mutation.1: Interaction of radiation in cell: Physical and biological response of ionizing radiation Cells are more radiosensitive during the phase of cell division known as mitosis. but the magnitude of the effect per unit dose differs. Highly differentiated tissues like muscle and brain are least radiosensitive. For example DNA single strand break. Hence rapidly dividing cells like intestinal epithelium. Approximately two-third of all radiation induced damage is considered to be caused by the hydroxyl free radical. LINEAR ENERGY TRANSFER The linear energy transfer (LET) is a parameter that describes the average energy deposition per unit path length of the incident radiation and it is expressed in keV/μm.1 presents the physical and biologic responses to ionizing radiation. The Fig. e). The LET of the X and γ rays and tissue penetration are listed in Table 2. The RBE is proportional to LET at the beginning. the RBE decreases with increasing LET. cataract formation and acute lethality etc. due to overkill.2: The relation between LET and RBE Table 2. Fig.2.2 100 Co-60 BIOLOGIC EFFECTS The harmful effects of radiation in human body are classified as (i) somatic effects and (ii) Genetic effects. RBE also depends on the total dose and dose rate of the radiation.5 70 Positron emitters 1000 5.8 65 I-131 511 3. Later it increases with LET. The relationship between RBE and LET is shown in Fig.4 43 Co-57 140 1. It is produced in an exposed 17 . Biological Effects of Radiation These effects or endpoint includes chromosomal mutation. The radiation effects. This means that radiation deposits excess energy than that necessary to kill the cell. suggesting deposition of higher energy in the tissue.1 below. which is relevant for low LET radiations (X.1: The LET of X and γ rays and tissue penetration in HVL X and γ LET(keV/μm) HVL(mm) in Tissue Source rays Energy (keV) 80 1. arises due to the damage of the somatic cell are called somatic effects. γ.0 38 Diagnostic X-rays 120 1. 2. 2. Beyond 100 keV/μm.5 46 Tc-99m 364 2. which is applicable to high LET radiations(α). coma etc.0 Gy All the above + manifestation of skin damage > 25 Gy All the above + severe depression. delirium.decades). Early Somatic Effects (Whole Body Irradiation) Somatic effects may appear immediately after exposure.0 Gy Severity of above effects increases + damage to blood forming organs (bone marrow. (Central nervous system syndrome[CNS]). vomiting . 8. about 50% of the exposed persons may die within 60 days (LD 50/60).2 shows the early somatic effects due to the acute whole body exposure to low LET radiation. *Source: AERB lecture notes 18 . Textbook of Radiological Safety individual during his life time.0 to 5.0 to 15. diarrhea (NVD) : complete recovery possible at low doses Above 3. infection. Table 2. The hereditary effects are due to damage to reproductive cells and manifest in the progeny of the exposed person. within a few hours to weeks or much later (after years . weight loss and fever. high fever (bone marrow syndrome). lymph node): death in 4-8 weeks possible (> 10%) 3.0 Gy Above + radiation sickness like loss of appetite. The early effects are due to an acute exposure (large doses over a short period of time) and attributed to depletion of cell population due to cell death. spleen. if the person receives the dose over a prolonged period. nausea. The amount of radiation damage depends on the rate at which the radiation is delivered. Death may occur in 1-2 weeks (100 %). The same dose delivered over several months allows the repair mechanisms to function fully. Death occurs in a few hours to days.1 Gy No detectable damage Above 0. High dose delivered in a short time may result in severe damages to tissues. somatic effects listed in the table may not manifest. Table 2. fatigue. Hence.1 Gy Chromosome aberrations detectable(1-2 dicentrics in 500 cells) Above 0. The magnitude of the somatic effects vary with nature of exposure (whole body or partial exposure).0 Gy All the above with increased severity + Anemia.0 Gy Severity of above effects increases + cells in the gastrointestinal system get severely damaged leading to gastrointestinal syndrome (GIS) like diarrhea.2: Early somatic effects due to acute whole body exposure to low LET radiation* Dose range Effect Less than 0. Above 10.5 Gy Above effect + transient reduction in WBC count: emporary sterility in males Above 1. it can produce certain serious local effects (Table 2.3). may lead to late effects. bone etc. The biological process required to transform the damaged cells to a cancer cell is very complex and the latent period may vary from 2-5 years for leukemia (blood cancer) and 5-30 years or more in the case of cancers of the lung. Table 2.3: Early somatic effects due to acute partial body exposure to low LET radiation Dose Region Effect 0. death of tissues Late Somatic Effects Exposure to low levels of radiation over a prolonged period. can affect the general characteristics of the offspring. But exposure of a part of the body to the dose will not be life threatening.15 Gy Testes Temporary sterility 3. the present 19 . which can be as long as 30 years. Biological Effects of Radiation Early Somatic Effects (Partial Body Irradiation) Partial body exposure to the above dose ranges produces only local effects. Since the threshold doses are much higher than the normal occupational dose.0 Gy Ovaries Temporary sterility 2.5 – 6.5 – 2. Late effects are characterized by latent period.5 – 6. Only that amount of radiation dose to reproductive organs. these effects may not occur from normal occupational exposure to radiation. All the early somatic effects do have a threshold dose. below which they do not occur. A whole body exposure to a dose of 4 Gy can be lethal. The seriousness of the local effects too depends on the dose rate and the period of exposure etc. Persons who recover from early somatic effects too may develop late somatic effects in life. which occurs up to the time of conception. Dose needed to produce cataract may be greater than 8 Gy of fractionated irradiation (not acute) with low LET radiation and the latent period may be 5-10 years. Beyond the threshold dose. The important late effects are cataract and cancer. blisters. However.0 Gy Testes Permanent sterility 1. However.0 Gy Ovaries Permanent sterility 3 Gy Hair follicles Epilation (fall of hair) 5 Gy Eye Cataract (after 2-3 years) 6 Gy Skin Reddening of skin (erythema) Permanent epilation 10-20 Gy Skin Burns. wounds. severity of the effect increases with the dose. Hereditary Effects Hereditary effects occur in the progeny of exposed individuals when reproductive cells carrying radiation-induced damages (mutations) participate in the process of fertilization. This is known as latent period. which is likely in diagnostic radiology and Nuclear medicine. blood changes. Examples are skin erythema.5 Gy) and soon after the dose is received. It may appear at higher doses (> 0. both for patients and occupational workers. cataract.5 Gy). Stochastic Effect A stochastic effect is one in which “the probability of occurrence increases with increasing absorbed dose rather than its severity”. This is known as Risk factor for the particular cancer. Hereditary and both early and late somatic effects of radiation can be classified into two categories. Textbook of Radiological Safety knowledge on hereditary effects is limited to laboratory animals. below which the effect is not seen. It is unlikely in diagnostic Radiology. organ atrophy. As such deterministic effects can be completely avoided by limiting the dose levels well below the threshold doses. Stochastic effects are the principle health risk from low level radiation. All these effects will definitely appear in the exposed individual. and reduction in sperm count. Deterministic Effect A deterministic effect (non stochastic) is one “which increases in severity with increasing absorbed dose in affected individuals”. Radiation induced cancer and genetic effects are examples for stochastic effects. fibrosis. No evidence for increase in hereditary effects was observed in human population exposed to both high and low dose of radiation. Hence the risk of stochastic effects cannot be completely avoided. as mentioned above are deterministic effects of radiation. However. The risk increases as the dose increases. It is very important at very low levels (< 0. namely (i) deterministic effects and (ii) stochastic effects. which may extend from 10 to 30 years. since tissue cells . Any dose. however small. The risk of inducing a particular type of cancer is measured by comparing the number of cancers produced in the irradiated population sample in excess of those expected in the same size of un irradiated population sample. The radiation dose required to produce such effects are very large and are likely to occur only as the result of radiation accidents and patients irradiated in radiotherapy. All somatic effects except cancer. 20 Leukemia has the highest risk factor among all cancers. it can be minimized to an acceptable level. It have threshold dose. epilation. Radiation Induced Cancer Radiation induced cancers may appear only some years after the radiation was received. is effective for a certain level of risk for induction of stochastic effects. It results in cell killing due to degenerative changes in the exposed tissues. It have no threshold dose and the chance of occurrence increases with dose and independent of sex and age. if the radiation dose received is above the respective threshold doses. during radiography. 2. Hence.3: The early and late biologic effects of radiation 21 with dose ranging from 0. To protect the future generations. Genetic Effects The radiation effects produced in the successive generation of the exposed individual are called genetic effects.000 children born to the survivors of atom bomb (500 mSv) do not show an increase in the incidence of genetic disorders. Fig. Only less severe effects are seen in the human population as a result of reproduction. Fig. Biological Effects of Radiation are rapidly dividing. 2. minimize the use of artificial radiations and adopt protection devices such as gonad shield in children. Epidemiological studies carried out on 30. As a result the biological code contained by the genes on the chromosomes gets altered and produce structural abnormality in the chromosome. summarizes both early and late biologic effects due to radiation exposure from 0. radiation induced cancers can not be prevented. It will be passed on to the future generations if reproduction takes place. There is no direct evidence of either elevated cancer risks or genetic disorders among human population exposed to low level radiation.001 mSv to 20 SV .001 mSv to 20 Sv. only be reduced by minimizing the radiation dose. Genetic effects are caused by radiation induced damage to the genes or chromosomes in the ova or spermatozoa. There is no safe dose limit and all doses of radiation carry some form of risk.3. The above damage is due to ionization and subsequent faulty recombination of the molecules which make up the chromosomes. Severe genetic effects are not observed due to short life span of the individual and inability to reproduce. This may lead to carcinogenesis through activation of oncogenes. 2. Thus presence of oxygen potentiates the radiation damage. and (iii) intermolecular and intramolecular cross linking. may result in irreversible structural changes in the molecule. which link the DNA base pairs. A double strand break are genotoxic lesions that can result in chromosome aberrations. . The 22 loss of change of base is considered as mutation. The rupture of hydrogen bond. Oxygen can cause the broken strand become peroxidized.4). DNA molecular breakage may occur as single strand breaks. inactivation of tumor suppressor genes. Fig. This includes (i) hydrogen bond breakage. two base pairs within DNA. and prevent it from rejoining. Cross linking may be between two DNA molecules. as result of reactive sites at the point of chain breakage. Textbook of Radiological Safety RADIATION EFFECTS ON DNA The ionizing radiation deposits energy in the DNA molecule and produce chemical changes. Single strand breakage between the sugar and the phosphate can rejoin. Single strand breaks are easily repairable than double strand breaks as far as the low LET radiation is concerned (Fig. 2. base loss or base changes occurring in DNA.4: Radiation action on DNA molecule: Single and double strand breaks Molecular cross linking is another common structural change. double strand breaks. DNA and a protein. or loss of herterozygosity. (ii)molecular dehydration. which leads to structural changes. Later a radiation dose of >250 mGy is required induce prenatal death and the spontaneous abortion rate is reported as 30-50%. Preimplantation begins with the union of the sperm and egg and continue until the zygote is embedded in the uterine wall. and the frequency of rings and dicentrics are scored. migration and differentiation. Chromosomal damage that occurs before DNA replication is called chromosome aberrations. The congenital abnormalities are low. congenital abnormalities. reduced intelligence. There is a strong force of cohesion between broken ends. The most sensitive time of exposure in humans is 12 hr after conception (when two pronuclei fuse together to one cell) and again at 30 and 60 hr. (ii)major organogenesis. During this period (9-14 days) the conceptus is more sensitive. radiation quality and gestation period of the pregnant women. In the later. As per the Bergonie and Tribondeau’s laws of radiosensitivity. any radiation damage may result in prenatal death.25 Gy can be estimated in the above method. only daughter of the one of the damaged chromatids pair is affected. highly differentiated cells are more radiosensitive. Biological Effects of Radiation Chromosome breaks produced by radiation do occur and can be observed microscopically. resulting in rings and dicentrics formation. The response after radiation depends upon the total dose. The type of damage includes prenatal death. as it is characterized by cell proliferation. growth retardation. growth impairment. microcephaly. and (iii) fetal stage. For this lymphocytes are cultured from human blood sample. The cells are arrested at metaphase. and type and location of the lesion. mental retardation. skeletal defects and carcinogenesis. though it is not completely absent. Total body doses > 0. Major organogenesis is the period between 2-8 wk (15-50 days) after conception. microphthalmia. when the first two divisions occurs. allowing karyotype to be performed. Exposure >100 mGy from the Hiroshima atomic bomb 23 . It is stimulated to divide. whereas that occur after DNA synthesis is called chromatid aberrations. These stages vary with radiosensitivity and result in different radiation response at each stage. RADIATION EFFECTS IN UTERO Developing embryo is extremely sensitive to ionizing radiation. Animal study revealed an increase in the spontaneous abortion rate after a dose of about 50-100 mGy during the preimplantation period. Chromosomal aberrations in human lymphocytes can be scored and used as a biological dosimeter to estimate radiation dose. dose rate. Repair of chromosomal aberrations depends on stage of the cell cycle. It is the critical period for radiation induced birth defects in human. Gestational periods is divided into three stages namely (i) Preim- plantation. genetic aberrations and an increased cancer risk. The embryonic malformations includes cataract. and (iii) revised model projects risk beyond the period of observation. linear quadratic and quadratic as shown in Fig. The fetus stage is between 50-280 days. prenatal death and congenital anomalies are negligible. The damage manifests later in life as behavioral alterations or reduced intelligence (IQ). Scientists have developed dose response models to predict the risk of cancer in human populations. 24 . There is risk of childhood leukemia is significant. 2. (ii) large number of cancer cases is seen among bomb survivors. A linear quadratic dose response model predicts lower incidence of cancer than the linear model at low doses and higher incidence at intermediate doses. 2. However growth retardation. that a given individual will incur a deleterious effects as a result of a dose of radiation. The reasons for the above are (i) revised neutron dosimetry which incorporated greater risk from low LET radiation. which resulted an increase in risk estimation.5: The linear and non linear models of radiation effects A non threshold linear curve overestimates the incidence of cancer at lower doses from low LET radiation. Exposures in excess of 1Gy are associated with a high incidence of CNS abnormalities. Hence. abnormalities of the nervous system and sense organs are the primary. RADIATION RISK Radiation risk is a probability.5. These models led to dose response curves. The risk estimates were revised in 1990 after reassessing the Japanese atomic bomb survivors. Fig. whose shape are non threshold linear. Textbook of Radiological Safety resulted an increase in the incidence of microcephaly. it is used in radiation protection for estimating risk. due to low level radiation exposure. It includes (i) somatic risk (ii) genetic risk and (iii) fetal risk. which is explained in later paragraphs.5).2). The Fig. (a) (b) Fig.6(b)). Biological Effects of Radiation Risk Models There are two type of risk models namely (i) Mutiplicative. and (ii) Additive risk models (Fig. the excess risk is a multiple of the natural age specific cancer risk for a given population. The additive risk model which predicts a fixed increase in risk unrelated to the spontaneous age-specific cancer risk at the time of exposure (Fig. For example. It is the ratio of the cancer incidence in the exposed population to that in general population. predicts a 20 % (120/100) increase over the spontaneous rate of cancer incidence. 2.6(a) describes the differences in magnitude of the projected cancer risk for a given exposure at different ages.2 To detect the above relative risk (1.6: The multiplicative model and additive model Relative Risk Relative risk (RR) is another way of expressing the risk from radiation in an exposed population. with a statistical confidence of 95% (p< 0. after exposure. 25 .2-1=0. The multiplicative model predicts that.6). one must require a study sample of population of >10000.when the spontaneous incidence in the population is 2 %. In this model a constant increment in incidence is added to the spontaneous disease incidence through out the life. after a latent period. It accounts for age and cancer risk at the time of exposure. The necessary modification in the risk estimate is provided by the BEIR report. The excess relative risk = RR-1= 1.2. Both models do not describe cancer risk adequately. 2. The risk increases with age (predicts greater risk at older age). 2. a relative risk of 1. 2. Other health effects (such as heart disease and stroke) occur at higher radiation doses. What is the risk of developing cancer in the next 40 years. It supports a “linear-no-threshold” (LNT) risk model—that the risk of cancer proceeds in a linear fashion at lower doses without a threshold and that the smallest dose has the potential to cause a small increase in risk to humans.1 × 4 × 10-4 = 12 × 10-4 If 10000 people are exposed to a dose of 0.Sv and the latency period is 10 years. which is 4 % per Sv for a population of adult workers and 5 % per Sv for the whole population (includes young ones). It is expressed as number of excess radiation induced cancers per 104 people /Sv-year. but at low doses the number of radiation-induced cancers will be small. it accounts for both cancer incidence and cancer mortality. from a dose of 0. Example 1: The risk is 4 per 10. It is unlikely that there is a threshold below which cancers are not induced. This is in agreement with the ICRP estimate. As per the report the radiation induced mortality at low exposure level is 4 % per Sv and it is 8% for high dose rates. to which linear quadratic model is recommended. 12 additional cases of cancer will be seen in that population in the next 40 years. the risk of adverse heritable health effects to children conceived after their parents have been exposed is very small compared to baseline frequencies of genetic diseases in the population.000 person . The BIER V committee advocate the linear dose response model for all cancers except leukemia and bone cancer. Textbook of Radiological Safety Absolute Risk Another way of expressing risk is the absolute risk. The report also concludes that with low dose or chronic exposures to low LET irradiation. that can be made between low doses of radiation and non cancer health effects. BEIR VII report (2003) gives the most up-to-date and comprehensive risk estimates for cancer and other health effects from exposure to low level ionizing radiation.1 Sv. There is a linear dose-response relationship between exposure to ionizing radiation and the development of solid cancers in humans.1 Sv Risk = 4 × 10-4 Risk of developing cancer = 30 × 0.1 Sv? Actual duration = 40 – 10 = 30 years Dose = 0. but additional data must be gathered before an assessment of any possible dose response. 26 . BEIR Report V and VII Risk Estimate The National research council committee on the Biological effects of ionizing radiation (BEIR) report V has been published in 1990 on the title “Health effects of exposure to low levels of ionizing radiation”. That is. Exposure in infants.4 below. Lower doses would produce proportionally lower risks.5% higher than for men in the solid tumors. For example. Biological Effects of Radiation Radiation related cancer mortality risks for woman averaged is 37. Cancer induction is the largest risk of radiation.0 × 10-2 Sv-1 for fatal cancer 0. it is predicted that approximately one individual in 1000 would develop cancer from an exposure to 10 mSv. Genetic risk analysis assume that the (i) exposed population consists of all ages and both sexes and (ii) severe genetic effects in the next two generations. Caner risk are higher for children than for adults. The doubling dose for humans is estimated as ~1Gy per generation. BEIR VII lifetime risk model predicts that approximately one individual in 100 persons would be expected to develop cancer (solid cancer or leukemia) from a dose of 100 mSv while approximately 42 of the 100 individuals would be expected to develop solid cancer or leukemia from other causes. breast tissue. gastrointestinal tract mucosa. The genetically significant dose (GSD) is an index to estimate the radiation induced mutation in germ cells of a given population. Radiation may induce both benign and malignant tumors with latent period. Cancer risk is estimated as 4 × 10-2 /Sv. which 27 is extrapolated from animal data. gonads and lymphatic tissue are most susceptible for cancer induction. The spontaneous mutation rate is about 5 × 10-6 per locus and 15 × 10-4 per gamete for chromosome abnormalities. Somatic Risk Somatic risks may arise from both stochastic and deterministic effects. Female infants have almost double the risk of males. The sensitivity of a population to radiation induced damage is measured by doubling dose.4: ICRP 60 Risk factors Assumed radiation risks ICRP Publication 60 Workers 4.8 × 10-2 Sv-1 for severe genetic effects 5. It is defined as the dose required per generation to double spontaneous mutation rate.3 × 10-2 Sv-1 for severe genetic effects Embryo-fetus Not specifically stated Genetic Risk Genetic risk is the result of radiation exposure to the gonads.8 × 10-2 Sv-1 for non fatal cancer detriment 0. . as compared to adults.0 × 10-2 Sv-1 for fatal cancer Members of the public 1.0 × 10-2 Sv-1 for non fatal cancer 1. The ICRP recommended risk factors are given in the Table 2. produces 3-4 times the cancer risk. Table 2. Bone marrow. only when doses are >100 mGy. Fetus Risk Doses lower than 100 mGy generally carry negligible risk.02 % per 100 mGy) in the first generation. This will not put the fetus any significant increase in risk for congenital malformation or growth retardation. The relative incidence of various health effects with radiation exposure in utero at various stages of gestation are shown in Fig. For example radioiodine can cross the placenta and concentrate on the fetal thyroid after 13 th week of gestation. The usual diagnostic and occupational exposures would not be expected to result in any significant genetic risk to their progeny. Hence the 100 mGy dose can cause additional genetic disorders of about 0. It is estimated that the excess risk of childhood cancer from in utero irradiation is approximately 6% per Gy.02-5)/5) × 100} only. There are two type of radiopharmaceuticals: (i) those that cross placenta and (ii) those that remain on the maternal side. 2. To avoid congenital abnormalities abortion may be advised. . The fetal dose from Medical Diagnostic procedures rarely exceeds 50 mGy. 2.7.7: Health effects of radiation exposure in utero at various stages of gestation Radiopharmaceuticals administered to pregnant women is associated with radiation risk to the fetus. Textbook of Radiological Safety A dose 100 mGy would produce only about 200 additional genetic disorders per 1 million live births (0. It may be 55 to 75 % between 14 and 28 22 weeks of gestation. This may result in hyperthyroidism or ablation. whereas the normal incidence is about 1 in 20 (5%). Fig.4 % {(5. ) Churchill Livingstone 2007. If there is a missed period. but this was reduced to 10 days to account for the variability of the human menstrual cycle. lecture notes 2008. BEIR VII: Health Risks from Exposure to Low Levels of Ionizing Radiation. Example 2: Calculate the risk for radiation workers and the public for a annual effective dose limit of 20 mSv and I mSv respectively (Assume the risk coefficient is 4 × 10-2 per Sv).02 Sv Annual risk = 0. if so justified. one should confine the radiological examination of the lower abdomen and pelvis to the 10 day interval following the onset of menstruation. 500 Fifth Street. every care should be taken to explore other methods of getting needed information by using non radiological examinations. In most situations. the effect of damage to these cells is most likely to take the form of failure to implant. Total body fetal dose estimate ranges from 0. BIBLIOGRAPHY 1. Worker: Annual dose limit = 20 mSv = 0. there is growing evidence that a strict adherence to the “ten day rule” may be unnecessarily restrictive.001 × 4 × 10-2 = 4 × 10-5 TEN DAY RULE AND ITS PRESENT STATUS ‘Ten day rule’ was postulated by ICRP for woman of reproductive age. When the number of cells in the conceptus is small and their nature is not yet specialized. Principles of Radiological physics. 3. National Academies Press. Since organogenesis starts 3 to 5 weeks post conception. Biological Effects of Radiation Estimate shows that the dose to the fetal thyroid may range from 230 to 580 mGy / MBq for gestational period of 3 and 5 months. malformations are unlikely or very rare. Thus. NW.edu. Donald TG. or of an undetectable death of the conceptus. it was felt that radiation exposure in early pregnancy couldn’t result in malformation.nap. 800: 624-6242. The main risk is that of abortion if the radiation exposure results in death of the conceptus.” The original proposal was for 14 days. It states that “whenever possible. It requires a fetal dose of more than 100 mGy for this to occur. AERB short course on radiation safety. Paul C. a female should be considered pregnant unless proved otherwise. www. Martin Vosper. it was suggested to do away with the 10 day rule and replace it with a 28 day rule. 2. (5th edn. In such a situation. This means that radiological examination.001 Sv Annual risk = 0.27 mGy / MBq during pregnancy.072 to 0.02 × 4 × 10-2 = 8 × 10-4 Public: Annual dose limit = 1 mSv = 0. can be carried throughout the cycle until a period is missed. Based on this. 29 . DC 20001. Washington. the focus is shifted to a missed period and the possibility of pregnancy. 30 . Upton AC. (2nd edn. (2nd edn. Committee on the biological effects of ionizing radiations. Edwin ML. Seiber JA. Textbook of Radiological Safety 4. John MB. Health effects of exposure to low levels of ionizing radiation (BEIR V). Mettler FA.). co. 1990.). National research council. 5. 1995. 6. Washington. Medical effects of ionizing radiation. DC: National Academy Press. The essential physics of medical imaging. Lippincott Williams & Wilkins 2002. Philadelpia:WB saunders. Jerrold TB. lesser will be the radiation dose. in addition to the use of foot switch. Diagnostic X-ray machines typically produce high exposure rates over brief time intervals. when personnel are nearer to the machine. the radiation dose received also increases. The following paragraphs will explain their role and application in medicine. Hence. Techniques to minimize time in a radiation field should be recognized or practiced. TIME The total dose received by a radiation worker is directly proportional to the total time spent in handling the radiation source. For example. The radiation level at the location of the radiographer is 100 mR/h. Hence. chest X-ray produces an skin entrance exposure of 20 mR in less than 1/20 of a second. Hence both the knowledge of exposure rate and how it changes with time are important elements in reducing personnel exposures. one has to plan the radiation procedure. For example. practice the procedure with out radiation and share the essential duties. minimize the time spent in any radiation area. to reduce radiation exposure. The time spent near the radiation source can be minimized by under standing the task to be performed and the suitable equipment to complete them in short interval with safety. The exposure rate at 1m from a patient injected with 20 mCi of Tc-99m. equivalent to 1440 R/hr. for bone scan is 1 mR/hr. All radiation sources do not produce constant exposure rates. and (iv) Contamination control. Lesser the time spent near the radiation source. radiation exposure can be minimized by not energizing the X-ray tube. Example 1: A radiographer is performing barium examination under fluoroscopy and the equipment is ‘ON’ for 3 minutes for each examination.5 mR/hr after 2 hours. Chapter 3 Radiation Exposure Control The four principal methods by which radiation exposures to persons can be minimized are (i) Time (ii) Distance. It reduces to 0. Hence. fluoroscopy screening time should be kept short by the use of last frame hold facility. How many such procedures the radiographer can carry out per week? . due to decay and urinary excretion. (iii) Shielding. Nuclear medicine procedure produce lower exposure rate for extended periods of time. As the time spent in the radiation field increases. then the exposure rate X2 at another distance D2 is given by 2 ⎛D ⎞ X 2 = X1 ⎜ 1 ⎟ (1) ⎝ D2 ⎠ Doubling the distance from the X-ray source decreases the X-ray beam intensity by a factor of 4.18 R-cm2/mCi-hr for I-131) Exposure level at 30 cm from 10 mCi of I-131 source = 2.024 R/hr = 24 mR/hr 2000 mR Weekly permissible exposure = 40 mR 50 weeks 40 mR Allowed time of work = = 100 minutes 24 mR/hr DISTANCE Radiation intensity (exposure rate) from a point source decreases with distance.18 × 10 mCi /(302) = 0. 3. If the exposure rate is 100 mR/hr at 1 m. It is governed by the inverse square law. Larger the distance. due to divergence of the beam. whose . the number of procedures the radiographer can associate with 40 mR in one week = =8 5 mR Example 2: An operator is handling 10 mCi of I-131 source with 30 cm tongs. Textbook of Radiological Safety The annual equivalent dose limit prescribed for the radiographer is (occupational worker) 20 mSv = 2000 mrem ≈ 2000 mR 2000 mR The permitted weekly dose = = 40 mR 50 weeks Exposure rate at the location of radiographer = 100 mR/h 100 = mR/min 60 100 mR The exposure in each procedure = × 3 min = 5 mR 60 min Hence. lesser will be the 32 radiation dose. Γ20 =2. This relationship is valid for point sources only.1). If the exposure rate is X1 at distance D1. which states that the exposure rate from a point source of radiation is inversely proportional to the square of the distance. then it will be 25 mR/hr at 2 m (Fig. Within how much time the technician will receive the weekly permissible equivalent dose? (assume 1R=1 rad. all personnel should stand as far away as possible during X-ray procedures.1: The inverse square law: As the distance increases by a factor 2. the radiation intensity decreases by a factor of 4 In diagnostic radiology at 1m from a patient. during patient imaging and distance is the only primary dose reduction method. Table 3. Personnel should stand at least 2 m from the X-ray tube and the patient and behind the shielded barrier or out of the room. imaging rooms should be designed to maximize the distance between the source and control console. Unshielded radiation sources should never be manipulated by hand.1-0. the scattered radiation is about 0. A typical exposure rate with distances. whenever possible. Because most of the time the technologists spend their time at the control console for acquisition and image processing.1: Exposure rate with distance in nuclear medicine Radionuclide10 mCi Exp rate (mR/hr) at 1cm Exp rate (mR/hr)at 10 cm Ga-67 7500 75 Tc-99m 6200 62 I-123 16300 163 I-131 21800 218 Xe-133 5300 53 Tl-201 4500 45 Example 3: The exposure rate from a fluoroscopic X-ray machine is 5 R/ min at 50 cm. Thus the relationship is not valid near (<1 m) a patient injected with radioisotopes. Hence. Radiation Exposure Control dimensions are very small compared to distance under consideration. Fig. for a nuclear medicine facility is given in Table 3. 3. What would be the exposure rates at (i) 40 cm. Tongs or other handling devices are used to increase the distance between source and hand. and (ii) 60 cm? 33 . Hence.15% of the intensity of the primary beam. The nuclear medicine technologists receive the annual dose mainly by patient imaging. since the exposure rate decreases less rapidly than inverse square law. In nuclear medicine it is difficult to shield the technologist from the radiation emitted from the patient.1. Γ = 13 R-cm2/mCi-hr for Co-60) Exposure level at 1 cm from 5 mCi Co-60 source = 13 × 5= 65 R/hr X1 = 65 R/hr. X2 = ? ⎡ X 1 × ( D1 )2 ⎤ ⎡ 65 R / hr × ( 1 cm )2 ⎤ ⎣ ⎦ ⎣ ⎦ X2 = = = 0. D1 = 50 cm.2) of thickness x. D2 = 60 cm . As a result. X1 = 5 R/min. D2 = 40 cm . staff and the public. X2 = 2 mR/hr ? ⎡ X 1 × ( D1 )2 ⎤ ⎣ ⎦ X2 = ( D2 ) 2 ⎡ 46900 mR / hr × ( 1 cm )2 ⎤ 2 mR/hr = ⎣ ⎦ . D2= ? cm. The material that attenuates the radiation exponentially is called a shield and the shield will reduce exposure to patients. D1=1 cm. the transmitted beam will have less number of photons. X1 = 5 R/min. 3. adequate shielding must be provided. X2 = ? ⎡ X 1 × ( D1 )2 ⎤ ⎡ 5 R / min× ( 50 cm )2 ⎤ ⎣ ⎦ ⎣ ⎦ X2 = = = 7. D2 = 10 cm . When a photon passes through an absorber (Fig.81 R/ min ( D2 ) ( 40 cm ) 2 2 2. This can be represented by the relation 34 I = I0 e.9 R/hr = 46900 mR/hr X1 = 46900 mR/hr.53 m ( D 2 cm ) 2 SHIELDING When maximum distance and minimum time do not ensure an acceptably low radiation dose. X2 = ? ⎡ 5 R / min× ( 50 cm )2 ⎤ ⎣ ⎦ X2 = = 3. both absorption and scattering takes place.65 R/ hr = 650 mR/hr ( 2) ( ) 2 2 D 10 cm Example 5: What would be the distance required to reduce the radiation level from a 10 mCi Ir-192 source to 2mR/hr? (Given. D1 = 50 cm.69 R-cm2/mCi- hr for Ir-192) Exposure rate at 1cm from 10 mCi Ir-192 source = 4. Textbook of Radiological Safety 1. Γ=4. D1 = 1 cm.69 × 10 = 46. D2 = 153 cm or 1. so that radiation beam will be sufficiently attenuated.47 R/ min ( 60 cm ) 2 Example 4: What would be the radiation level at 10 cm from a 5 mCi source of Co-60? (Given.μx (2) . 2: Attenuation of radiation through a shielding material HALF VALUE LAYER The linear attenuation coefficient is defined as the reduction in the radiation intensity per unit path length and is expressed in cm-1. Fig. Radiation Exposure Control where I is the number of transmitted photons.2 indicates the decrease of radiation intensity with increasing HVT’s (for heavily filtered X-ray beam). the reduction factor offered by n HVT of the shielding material is 2n. 35 . e is the base of natural logarithm and μ is the linear attenuation coefficient.5 to 3.0 cm.693 μ= (3) HVL The thickness of material that attenuates radiation beam by 50 % is the half-value layer or half value thickness (HVT). The Table 3. The linear attenuation coefficient is related to the term half value layer (HVL) as follows: 0. I0 is the number of incident photons. the HVL for soft tissue ranges from 2. The reduction factor offered by one HVT is 2 and by 2 HVT is 2 × 2 or 22. 3. Hence. For diagnostic X-ray beam energies. 693 / HVT ) = 3.303 = ( 0. both HVT and TVT depend upon the energy of the incident radiation and the shielding material. X-ray attenuation is primarily by photoelectric 36 effect and to some extent by compton effect. of HVTs % transmission 0 100. and by 2 TVT is 10 × 10 or 102 and 10n for n TVT and so on.2: Relation between half value layer and % of transmission No.303 TVT = (4) μ 2. mm HVT TVT HVT TVT HVT TVT IR-192 43 152 13 43 6 16 CS-137 48 175 16 53 6. In diagnostic energy range.25 5 3.5 22 Co-60 62 218 21 71 12 41 The shielding type.32 HVT For a given material. Table 3. which gives the thickness of material that attenuates the radiation beam by 90 %. The reduction factor offered by one TVT is 10.0 3 12.50 4 6. Hence. steel and lead. thickness and the location are functions of photon energy. mm Lead.0 1 50.Cs-137 and Co-60 (IAEA Safety series 47) Source Concrete. the reduction in intensity depends upon the nature and thickness of the shield and energy of the radiation. source geometry and exposure rate. Table 3. Photoelectric effect varies with .12 6 1. lesser the radiation. The thicker the shielding.56 10 0. number. intensity.3: HVT and TVT values of concrete. mm Steel.0 2 25. steel and lead for Ir-192.3 shows the HVT and TVT values for gamma rays with respect to concrete.09 Tenth Value Layer There is another interesting term called tenth value layer (TVL or TVT). The TVT and HVT can be related by using the equation: 2. Textbook of Radiological Safety Table 3. lead is used as shielding material to reduce the volume of shielding. personnel radiation must be kept As Low As Reasonably Achievable. (ii) scattered radiation and (iii) leakage radiation. lead and steel are used as primary barrier shielding material.3). number of patients per week. are the most commonly used materials for shielding radiation exposure in medicine. and lead glass are also used as shield. Lead. and considered low speed film-combination. . the annual dose limit is 100 mrem per year. The corresponding limits in USA is 50 mSV and 1 mSv respectively and (iii) The dose equivalent to the controlled area (restricted entry) should not exceed 0. When the report was made single phase generator was in use.3 ⎝ 13 ⎠ In other words. neglected the image receptor attenuation. gonad shield.02 mSv per week. The scattered and leakage radiations are jointly called as secondary radiation (Fig.6 mSv per week. Primary Radiation The radiation passing through the open area defined by the collimator of the X-ray tube / radiation equipment is called primary radiation. 3. Concrete. The corresponding limit for the uncontrolled area is 0. and fraction of time the radiation beam is directed towards any particular location. The factors to be considered while determining the amount and type of shielding are (i) ALARA principle. The NCRP-49 (1976) describes the structural shielding design and evaluation for Medical use of X-rays and γ rays of energies up to 10 MeV. SOURCES OF EXPOSURE The radiations used in medical application appear in three forms namely (i) primary radiation. depending upon the structural and spatial considerations. strict adherence of NCRP-49 would result in expensive shielding procedures. lead gloves. with their atomic numbers. (ii) Personnel exposures should not exceed the regulatory limits. Hence. Radiation Exposure Control atomic number (Z) and is proportional to Z 3. The reduction in intensity caused by lead over aluminium is given by 3 ⎛ 82 ⎞ ⎜ ⎟ = 250. 37 lead and steel can be used as primary barriers. For example concrete is preferred for the construction of walls and ceiling. This is 30 mSv for occupational workers and I mSv for the general public in India. Hence. lead bricks. because it is cheep. 1 gm/cm2 of lead will be as effective as 250 g/cm2 of aluminium. one can compare lead (Z=82) and aluminium (Z=13) as shielding material for the same thickness (g/cm2). Lead aprons. Whenever there is shortage of space. The amount of primary radiation depends on output. Hence in many situations. brick and concrete. the quality of the scattered radiation is assumed to be same as that of the incident beam. which varies with scatter angle and beam quality. and (iv) scattering angle. for a field area of 20 × 20 sq cm. 3. Textbook of Radiological Safety Fig. scattered and leakage radiations Scattered Radiation Scattered radiation from a patient. (iii) field size. causing a portion of the primary radiation to get redirected. Leakage Radiation Leakage radiation is the one that emanates from the source housing. In diagnostic radiology. It is about 0.1-0.3: The various sources of exposure namely primary. collimator or shield is also a source of radiation. tabletop. the ratio of scattered dose to the incident dose is denoted as α. Scattered radiation must be considered as a separate source. The α is assumed to be 0. The quality of the leakage radiation is approximately the . The maximum energy of the 90° scattered photon is 500 keV. The fluence of scattered radiation depends on (i) the volume of the patient irradiated. (ii) spectrum of the primary beam.15% of primary at 1m from patient. Scattered radiation is due to the interaction of the primary with the patient. The penetrating power of scattered beam is greater at smaller scatter angle.1% of the primary for 90 degree scatter. Also greater fraction of primary is scattered at smaller angles. The transmission of the above beam is similar to that a 500 kVP primary beam. for radiation safety purposes and in general it has low energy. other 38 than primary. In mega voltage radiations. This will be applicable to all types of X-ray tubes except mammography. Leakage Limits for Cobalt Teletherapy For Cobalt teletherapy. In the beam on position. but within a circular plane of radius 2 m that is perpendicular to and centered on the central axis at the normal treatment distance. In addition. the leakage radiation measured at a distance of 1m from the source shall not exceed either 10 mGy/h or 0. shall not exceed 0. In mammography the corresponding leakage limit is 0.5% of the useful beam dose rate at the treatment distance. The NCRP report 102 supersedes the previous NCRP report 33 and recommend the following limits: 1.2% of the useful beam dose rate at the treatment distance. However. these assemblies shall limit exposure rate to 30 R/h at 5 cm from the surface of the assembly. the leakage radiation measured at a distance of 1 m from the source shall not exceed 20 μGy/h.1% of the useful beam air kerma rate at 1 m from the source.02 mGy at 5 cm from any point on the external surface of X-ray tube housing (AERB /SC/MED-2).1 R in any 1 hour at any point 5 cm from the source assembly. Since it passes through the source housing. the recent NCRP report 102 summarizes the cobalt teletherapy leakage as follows: The leakage dose rate from the source housing with the 39 . 5-50 kVp: The leakage exposure rate shall not exceed 0. 50-500 kVp: The leakage exposure rate at a distance of 1 m from the source shall not exceed 1 R in any 1 hour. LEAKAGE LIMITS Leakage Limits for X-ray Housing The leakage radiation through the protective X-ray tube housing in any direction. 2. 3. At any readily accessible position 5 cm from the surface of the housing the leakage radiation shall not exceed 200 μGy/hr. Greater than 500 kVp: The absorbed dose rate due to leakage radiation (excluding neutrons) at any point outside the maximum field size. its effective energy is very high in diagnostic X-rays. in the beam off position.0 m from the X-ray target. whichever is greater (AERB/SC/MED-1). the leakage dose rate from the source assembly at any point at a distance of 1 m from the electron path between the source and the target shall not exceed 0. Except for the area defined above. Radiation Exposure Control same as that of the primary beam. averaged over an area not larger than 100 cm2 with no linear dimension greater than 20 cm. The neutron contribution to the dose within the useful beam shall be kept well below 1% of the X-ray dose. shall not exceed an air kerma of 1 mGy in one hour at a distance of 1. Outside the useful beam. the neutron dose should be reduced to as low as practicable. PROTECTIVE BARRIER DESIGN Protective barriers are designed to ensure that the dose equivalent received by any individual does not exceed the applicable maximum permissible value. In the case of emergency storage container or an in house transport container. concrete. At 1m from the centre of the storage the air kerma rate of leakage radiation must not exceed 20 μGy/hr.000 rad /h at 1m. emergency storages and in house transport containers. leaded acrylic and gypsum. The required barrier against leakage and scattered (stray) radiation is called the secondary barrier. A barrier sufficient to attenuate the useful beam to the required degree is called the primary barrier. leaded glass. The air kerma rate of the leakage radiation measured at any readily accessible position 5 cm from the surface of the storage must not exceed 200 μGy/ hr. 1. 3. Work Load (W) Workload is a measure of expected exposure levels obtained from the patient 40 load and machine ON time. Leakage Limits for Brachytherapy The Brachytherapy source storages (LDR/HDR equipments). With the beam in the ON position. at a distance of 1 m from the source. and 2. the leakage from the source housing shall not exceed 1 rad/h at 1m from the source. In addition. for sources that give rise to a useful beam dose rate of less than 10. It is expressed in mA-min/week in diagnostic . the leakage dose rate from the source housing shall not exceed 0.1% of the useful beam dose rate. both measured at a distance of 1 m from the source. The amount of attenuation necessary depends on five factors: • Workload • Use factor • Occupancy factor • Distance • Radiation exposure level. Textbook of Radiological Safety beam in the OFF position shall not exceed 2 mrad/h on the average and 10 mrad/h maximum in any direction. The following materials are used as barriers: Lead (Most commonly used material because of its high attenuation properties and low cost). must meet the following limits for leakage radiation. the air kerma rate of the leakage radiation measured at a distance of 5 cm from the surface of the container must not exceed 2 mGy/hr and at a distance of 1 m from the source of the container must not exceed 100 μGy/hr (AERB/SC/MED-3). Barrier should protect all the three types of radiation namely primary. scattered and leakage radiations. shops. An area below ground would have no occupancy at all and therefore T would equal zero. workload. it is expressed in weekly dose (Gy/week) delivered at 1m from the source. Radiation Exposure Level (XT or P) It represents the exposure (mR/week) at a given location in an adjacent area. The use factor for different barriers are as follows: • Primary barrier: U=0 to 1 • Secondary barrier: U=1 • Floor: U=1 • Walls: U=1/4 • Ceiling: U=1/4 to 1/2 Occupancy Factor (T) The occupancy factor relates to the amount of time rooms adjacent to the treatment room are occupied. Use Factor (U) It is the fraction of the operating time during which the radiation under consideration is directed towards a particular barrier (wall) per week. Radiation Exposure Control radiology (< 500 kVp). reception. control room Corridor 1/4 (Partial occupancy) Toilet. bath rooms. It is defined as the fraction of the operating time during which the area of interest is occupied by the individual. children 1 (Full occupancy) play areas. 41 . store rooms 1/16 (Occasional occupancy) Distance (d) It is the distance in meters from the radiation source to the area to be protected. Table 3. This can be obtained by multiplying the number of patients treated per week with dose delivered per patient at 1m. Areas that are intermittently occupied. For mega voltage machines.4: Occupancy factors (NCRP 49) Type of occupancy Occupancy factor (T) Office. primary. staff rooms. Inverse square law is assumed for both primary and stray radiation. Table 3. which can be obtained by multiplying the maximum mA with beam on time in minutes/week. scattered and leakage level and corresponding distance to the point of interest. such as corridors. It is function of technique.4 shows type of occupancy and occupancy factors (NCRP 49). outside areas with seating. would have a slightly greater occupancy and an area such as an office even greater. and 50 mAs per film will be calculated as follows: W = (20 patients/day) × (5 days/week) × (3 films/patient) × (5 mAs/film) × (1 min/60 s) = 25 mA-min/week In general higher kVp settings decrease the workload. For example.min/week. is the product of W and the tube current measured at 1m from the source. kVp and the . Otherwise it can be obtained from the graph between mR/mAs verses X-ray tube potential as a function of HVL (Fig.49).min/wk) × 60 × 5 (mR/mA. Table 3. The primary beam exposure per week (XP) at 1m from the source. These are overestimated values as it is based on slower (speed100) film-screen receptors. This will vary with field size. 3.5 (NCRP report No. For example an X-ray tube operating with a workload of 300 mA min/week with out put is 5 mR/mAs at 1m.min/wk) × 5 (mR/mAs) = 300 (mA.000 mA. The workload values for various types of radiographic rooms are given in the Table 3. at higher kVp. W (mA. 3 films per patient.min) = 90.3 films/patient 60 250 150 Fluoroscopy 24 750 300 General radiography 24 1000 400 Special procedures 8 700 280 Shielding Calculation for Diagnostic X-ray The X-ray tube output (mR/mAs) is determined by direct measurement.min/week. min/wk). min/wk). The scatter fraction (S) is 0. the workload of a hospital with 20 patients per day. Textbook of Radiological Safety FACILITY DESIGN FOR DIAGNOSTIC X-RAYS Workload A busy diagnostic X-ray unit will have a workload of 1.000 mR/wk The exposure due to scattered radiation from the patient is a fraction of the incident primary exposure.4). This is due to (i) increase of output (mR/mAs) as the kVp increases and (ii) less attenuation of the incident beam by the patient reduces the mAs. whereas small clinics may have 100 mA.5: Workload for diagnostic X-ray Procedure Patient load/day W (mA.15% at 1m for a 42 400 cm2 field size at 125 kVp. then XP = workload × tube out put (5) = 300 (mA. 100 kVp 125 kVp Chest. scatter fraction.1. The scattered radiation (Xs) is the product of the incident exposure.15%) dsca = distance to the scatter For example.min. Hence.4: The Tube output in mR/mAs at a distance of 1 m with variation of HVL in mm for Al. by dividing by 60. for the maximum tube current and maximum kVp. 3. 43 . (Inverter generator. Hence. Radiation Exposure Control Fig. This can also be expressed in mR/mA.5 ⎠ ⎝ 100 ⎠ ⎝ 400 ⎠ = 135 mR/wk The exposure due to leakage radiation can not exceed 100 mR/hr at 1m from the source. the source of patient to distance is 180 – 30 = 150 cm ⎛ 90 .min). This may be written as 100 mR/mAmax – hour at 1 m.5% ripple. The patient thickness is 30 cm. 000 ⎞ ⎛ 0.2 mm Al inherent filtration) scattering angle. Then the leakage radiation (XL) per week is the product of the leakage radiation per mA min and the work load (Assume maximum m A=5. and the ratio of the maximum field size relative to 400 cm2. the scattered radiation exposure per week at 1m from the scatter is ⎛ Xp ⎞ field size XS = ⎜ 2 ⎟×S× (6) ⎝ dsca ⎠ 400 S = scatter fraction (0.15 ⎞ ⎛ 900 ⎞ XS = ⎜ 2 ⎟×⎜ ⎟×⎜ ⎟ ⎝ 1. W = 300 mA. a chest imaging is done at a SID of 180 cms with field size of 900 cm2 (30 × 30). 5 2 ⎟ + ⎜ 2.5 m from the chest stand.5m. dleak=2. and it is 0.5 2 ⎟ ⎣⎝ ⎠ ⎝ ⎠⎦ ⎝ ⎠ ⎝ ⎠ = 4156 mR/wk If Xlimit is the regulatory limit of radiation exposure for an partial occupancy (corridor. scatter and leakage radiations can be calculated.2 ⎞ X = ⎢⎜ 2. dsec=0. and U =1/4. since T =1/4 =0.2 mR/wk The total weekly exposure (X) is due to primary.25 = 2 (mR/wk) / 0. T=1/4) area. 3.67 mR/mA min) × W (mA min/wk) (7) = (1.67/5 mA min) × 300 (mA min/wk) = 100. then Xlimit = 2 (mR/wk) / T. Textbook of Radiological Safety Maximum leakage = 100 mR/mA × 60 = 1.5 2 ⎟ × ⎜ 4 ⎟ ⎥ + ⎜ 0. using this in the above equation.5: A model X-ray layout for barrier calculation ⎡⎛ 90. Fig. for uncontrolled area. then dpri=2.5m. 3.000 ⎞ ⎛ 1 ⎞ ⎤ ⎛ 135 ⎞ ⎛ 100. for an unshielded condition as follows: ⎛ exposure ⎞ ⎡⎛ X P ⎞ ⎛ X ⎞ ⎛ XL ⎞⎤ X⎜ ⎟ = ⎢⎜ ⎟ U pri + ⎜ S 2 ⎟+⎜ ⎟⎥ (8) ⎝ week ⎠ ⎢⎣⎜⎝ dpri ⎟ 2 2 ⎠ ⎝ dsec ⎠ ⎝ dleak ⎠ ⎥⎦ For example as shown in the Fig.5.25 = 8 mR/wk 44 .67 mR/mA min XL = (1.5. if a wall is positioned at 2.5 m from the source. 45 .93. Any way it is good to compensate increased workload of the future.5 inches thickness will offer the same protection. In multiple floor buildings.6) 4156 mR/wk T = 0. and hence that is the recommended minimal thickness. for 125 kVp from the table (3.ft) and 1mm of 1 lead thickness = 2 lb/sq ft. mammography unit operates within 35 kVp and 2 sheets of gypsum drywall (1. the attenuation offered by the screen-film is not accounted. Similar way the calculation is repeated for all the three walls (B.6 for various diagnostic energies for lead and concrete Xlimit = X e-(2. The HVL and TVL represents the half value layer and tenth value layer of the construction material of the barrier.5. For example.303 × T /TVL) by taking logarithm. The HVL and TVL are functions of the kVp and workload. the equation may be written as T = 0. Hence. In this calculation. Radiation Exposure Control The attenuation offered by the barrier is given by the relation Xlimit =X × e-μ ´ T (9) where the linear attenuation coefficient m = 0. the floor also should be considered for barrier calculations. All X-ray rooms need not be designed with concrete. The calculated shielding should extend up to a height of 7 feet from the floor. and D) and ceiling for the layout in Fig. Usually lead is specified in weight per square foot (lb/sq.6). C.303/TVL and T is the thickness of the attenuator. Instead of concrete if lead is used.1 mm 8 mR/wk This may be approximated as 18 cm or 7 inch concrete thickness.434 × ln (X / Xlimit) × TVL By substituting the values of exposure (X) and exposure limits (Xlimit) from above and TVL of concrete for 125 kVp (Table 3. to achieve the required radiological safety. then TVL =0. The values of the same is given Table 3. then T = 0. If brick is used as construction material then 10.6 cm thickness) is sufficient.434 × ln (4156/8) × 0. and solving for T. There is some practical difficulty in handling 2 lead greater than 2 lb/sqft.93 = 2. the wall thickness is over estimated. 3.303 × T/ TVL) Xlimit/X = e-(2.434 × ln × 66 = 179.693/HVL or μ = 2.52 mm. 6: HVL &TVL Values of lead and concrete for various diagnostic X-ray energies Peak voltage.0 53 125 0. and the detector plays the role of primary barrier. these measured data are provided as exposure lines from the isocenter of the gantry on a per slice basis for a given mAs (Fig.3 15 70 0.concrete kV (mm) (mm) (mm) (mm) 50 0.52 8.6).4 74 Shielding Design for Computed Tomography Work Load In the case of CT scan all the walls in the room are secondary barriers. Fig. Textbook of Radiological Safety Table 3.93 20. 3.06 0.0 66 150 0.17 0.99 22. fraction of head verses body scans. HVL.4 28 100 0. 3.28 0. and the average mAs per patient.30 0.6: CT scan layout: Exposure levels measured from the isocentre of the gantry in mR / hour 46 . The work load of a CT scan is calculated from average number of patients per week. Normally.Lead HVL.27 0.Concrete TVL.17 4. The measured data from a individual CT scan is required to determine the amount of scattered radiation. arising from the gantry.Lead TVL.88 16. 08 mR exposure at a distance of 3. 50 % of the scans are pre and post contrast and 50 % are with out any contrast (assume 1.5 cm or 5.93 = 1.13 mR for 100mAs.5 studies /patient) = 4500 slices /wk Shielding Calculation If each slice provides 0. For example.434 × ln (X / Xlimit) × TVL = 0. 5 rotation per patient with 250 mAs exposure per rotation. for 100 mAs.25. Now a days spiral CT scanners are used with increased acquisition speed and efficiency.90 mm This thickness is equal to 5 lb /sq ft.2 mm or 13. which demands high output X-ray tubes. for a occupancy of T=1/4=0.25 = 8 mR /week The required concrete shielding to reduce the exposure to 8 mR /week is T = 0. The corresponding weekly exposure is = 150 patient /week × (5 rotation /patient) × (0.5 studies /patient) W = (20 patients /day) × (5 day /wk) × (30 slices /study) × (1.31 inches If lead is used instead concrete.13 mR /100 mAs) × (250 mAs / rotation) = 243.5 m from the iocentre.434 × ln (900 /8) × 66 = 135. Radiation Exposure Control The workload of a head CT scan having 20 abdominal scan per day. Assume the exposure level at the wall level is 0. This is calculated by using the specific exposure rate constant (Γ) of the radionuclide. 30 slices per scan with 250 mAs per slice can be calculated as follows. Similar calculation needs to done for other walls. then the weekly exposure (X) is = 4500 slices × (0.08 /100mAs) × (250 mAs /slice) = 900 mR/week If the permissible limit is 2 mR /week. floors and ceilings. These scanners provides additional radiation burden to the workers and public. 47 .7 mR /week. a 64 slice CT scan handles 150 patient /week. FACILITY DESIGN FOR NUCLEAR MEDICINE The radiation exposure in nuclear medicine may vary from natural background to 100 R/hr. then Xlimit = (2 mR /week) / 0. which is defined as the exposure rate in R/hr at 1 cm from 1mCi of the radionuclide. then T = 0.434 × ln (900 /8) × 0. Example 6: A vial contains 100 mCi of I-131.Lead. Hence. However tungsten.47 7.25 5.3. If the exposure rate constant accounts photon energy greater than 20 keV.7.18 R-cm2/ mCi-hr. lead and lead glass are used as shielding materials to give personnel protection.75 1. It is expressed in Gy/week. the workload is obtained by multiplying number of patient treatment per week with delivered dose for each patient.66 3. if a nursing staff sit for 1 hour. then it is denoted as Γ20. .5 FACILITY DESIGN FOR RADIOTHERAPY 1. Table. mm I-131 2. if a linear accelerator treats 50 patients per day with dose of 4 Gy for each patient at 1m. there is no need to shield the walls of the nuclear medicine laboratory.8 mR In general. Textbook of Radiological Safety Exposure rate (R/hr) = ΓA/d2 (10) where A is the activity in mCi. Most of the low energy photons are attenuated by air and other intervening materials. These are used to design syringe shield. The Table 3. lead pigs.9 Ga-67 0. the exposure rate constant do not account photon energy below certain levels.0 Tc-99m 0.62 0.18 3. transport container and waste dust bin etc. Workload: In radiotherapy. and d is the distance in cm from a point source of radioactivity. Exposure = (2. then W = (4 Gy /patient) × (50 patient /day) × (5 days /week) = 1000 Gy /week NCRP Report 49 suggests a workload figure of 1000 Gy/week based on a dose of 4 Gy at 1 m per patient. assuming a five day week 48 for megavoltage facilities. For example.0 Cs-137 3. presents the exposure rate constants and HVL for various radioisotopes. having a Γ20 =2.0218 R = 21. L-bench.18 R-cm2 / mCi-hr) × (100 mCi) × (1 hr) × (1/100 cm2 ) = 0. What will be the exposure at 100 cm.7: Exposure rate constants and HVL for various radionuclides Radionuclide Γ20 (R-cm2 / mCi-hr) Half value layer.3 F-18 5.0 Mo-99 1. The occupancy factor is best defined as the fraction of an 8 h day or 2000 h year for which a single individual may occupy a particular area. Occupancy factors are based on local regulations and the specific conditions at the facility under consideration. . and lower for other walls. if specific values are not available. The time averaged dose rate (TADR) is the barrier attenuated dose rate averaged over a specified time.25 for one wall. who is there longest. When calculating the required barrier shielding it is useful to calculate the expected IDR for comparison with direct measurement after the facility has been built and the treatment unit installed. TADR is proportional to IDR.U and dose output rate (DR0) of the unit. averaged over one minute. is then determined from the IDR multiplied by the daily beam on time and then divided by the length of the working day: Daily beam on time TADR = IDR × (11) Length of working day or. The TADR is estimated over 8 h (R8). Use Factor: A use factor (U) describes the different beam orientations used for treatment when calculating the required barrier thickness for each beam orientation. The TADR. Radiation Exposure Control For dual energy machines the same workload figure of 1000 Gy/ week may be used. For megavoltage treatment units. by taking into account the workload and occupancy factor as unity. a facility performing a large number of total body irradiations may have a use factor greater than 0. in mSv·h–1 . It is most likely that the target group for shielding purposes will be non radiation workers employed by the hospital. NCRP Report 49 suggests a use factor of 1 for the floor with the beam pointing vertically down. and incorporates the W. NCRP Report 51 suggests an assumed workload of 500 Gy/ week for the higher energy. These use factors may depend on the particular use of the facility and also on the energy used. 2. IDR and TADR The instantaneous dose rate (IDR). It can also be expressed as follows: Wd U R 8 = IDR × (12) 8 × DR o 49 where R8 is the TADR averaged over an 8 h day. is the direct reading of the dosimeter that gives a reading in dose per hour. For example. If conventional treatment techniques are to be used. it is likely that the total beam-on time per day will be much less.25 for each wall and ceiling. although the unit may be in use for 8 h per day. or R8. and 0. 3. with the remainder of the workload being attributed to lower energy X-rays or electrons. Occupancy Factor: The occupancy factor (T) for an area should be considered as the fraction of time spent by a single person. the barrier thickness can be obtained. the weekly TADR (RW) may be calculated. or by the use of TVLs.15mSv·h–1.7 gives the model attenuation curves for various electron beam energies with concrete of density 2. U is the use factor (=1 for secondary barriers or the maze entrance). Fig. From the above. According to guidance from the United Kingdom. This takes into account the workload. DR0 is the dose output rate at 1 m. If B is the required attenuation of the barrier to reduce the primary beam dose to P. the area need not be supervised. and T is the occupancy factor. under broad beam geometry. then P ( d + SAD ) 2 WUT × B P= or B= (14) ( d + SAD ) 2 WUT where d is the distance between the isocentre and the area of interest outside the primary barrier in meters. W is the work load in Gy/week U is the use factor. By referring these attenuation curves. Textbook of Radiological Safety IDR is in mSv·h–1 averaged over 1 min at a point 0. if the IDR is less than 7. Primary Barriers Weekly Dose Rate Method Let P is the permissible dose equivalent limit for a given area in Sv/wk. The thickness of concrete required can be determined from attenuation graphs. in Gy for an 8 h day. SAD is the source to axis distance in meters.5 mSv·h–1 and the TADR is less than 0. The TADR 2000 is the time averaged dose rate estimated over 2000 h.5 mSv·h–1 or the TADR 2000 is less than 0. NCRP-51 has given the beam attenuation curves for various energies and barrier materials. 3.3 m beyond the barrier. for 40 hours. in Gy·h–1 or Sv·h–1. use factor and occupancy factors. with the machine operating at the dose output rate DR0 . The number of TVLs required to produce this attenuation is determined from: Number of TVL (n) = log10 (1/B) (15) 50 . as follows: ⎛ WU ⎞ R W = IDR × ⎜ ⎟ (13) ⎝ DR o ⎠ where W is the weekly workload.35 g/cc as barrier material. Wd is the daily workload defined at 1 m. 74 × 218 =1033 mm. the required thickness for the primary barriers is 4. the thickness of the barrier is calculated by using the equation S = T1+ (n – 1)Te (16) where. T= 1. Radiation Exposure Control Fig. The Table 3. W = 384 × 103 mGy/wk 0. T1 is the first TVL and Te is the equilibrium or subsequent TVL of concrete as given in the NCRP report No. 51 .8.9 presents the first TVL (T1) and subsequent TVL(Te) for various construction material with respect to energy.12 mSv/week. d = 3 m.12 × ( 3 + 0.35 g / cc as barrier material The Table 3.25 × 1 3 Number of TVL’s = log 10 (1/B) = log 10 (1/ 1. P ( d + SAD ) 2 Primary barrier B= WUT Assume P = 0.8).8 ) 2 B= = 1.81 × 105) = 4.25. presents the TVL values in meters for various construction materials.81 ×105 384 × 10 × 0. 3. U = 0.7: Attenuation curves for various electron beam energies under broad beam geometry. Then. with variable beam energies.51. for concrete with density 2. Therefore.74 The TVL for 60Co in concrete (density 2350 kg·m–3) is 218 mm (Table 3. Table 3. The number of TVLs of concrete is then determined from Eq.(15) in the same way as for the weekly dose rate method. Wall thicknesses determined for primary barriers will be more than adequate to shield against leakage and scattered radiation and no further calculations are required. in metres. b: Varian Associates. SAD is the source–axis distance (usually 1 m for linear accelerators). 52 . with variable beam energies (Source: IAEA safety series 47) Co-60a 4MVb 6MVb 10MVb 15MVb 18MVb 20MVb 24MVb TVL for concrete (density 2350 kg . m-3) (in mm) Primary beam 41 53 55 56 57 56 55 52 gamma/X-rays Secondary beam 40 47 45 46 47 47 49 51 gamma/X-rays a: NCRP report 49(1976). Nelson and LaRiviere (1984). m-3) (in mm) Primary beam 218 290 343 389 432 445 457 470 gamma/X-rays Leakage gamma 218 254 279 305 330 330 343 356 and X-rays (900) TVL for steal (density 7800 kg . in Sv·h–1. Width of the Primary Wall The primary barrier width is made equal to the maximum field size at the barrier plus 1 foot (0. d is the distance from the isocentre to the point of interest on the far side of the barrier. m-3) (in mm) Primary beam 71 91 98 105 108 111 111 107 gamma/X-rays Secondary beam 69 79 80 85 87 87 88 89 gamma/X-rays TVL for lead (density 11360 kg . in Gy·h–1. Most of the linear accelerator has 40 cm × 40 cm as maximum field size at 1m from the target.8: TVL values for various construction materials. DR0 is the dose rate at the isocentre (1 m). Textbook of Radiological Safety Instantaneous Dose Rate Method The barrier thickness required to reduce the IDR to an acceptable level on the far side of the barrier is determined as follows: The attenuation required BIDR is given by: PIDR ( d + SAD ) 2 B IDR = (17) DR 0 where PIDR is the instantaneous design dose limit.305 m) on either side to prevent radiation from leaking through the secondary barrier that abuts the primary. in m. The scatter primary ratio (α) is dependent on the energy of the X-ray beam and the scattering angle.305 × 2) = 0.566 d + (0. then P × dsca 2 × dsec 2 BP = (19) αWT × ( F / 400 ) where P.7 5.7 20 Concrete 46 44 Steel 11 11 Lead 5.61 (18) where d is the distance from the source to the barrier. steel (7.6 cm). in m.35 g/cm3). Then the horizontal barrier width (W). .7 18 Concrete 44 41 Steel 11 11 Lead 5. required is given by W = 0. W and T have the same meaning as above. Secondary Barrier for Scattered Radiation If Bp is the transmission factor required to reduce the scattered dose to an acceptable limit P in the area of interest.7 15 Concrete 44 41 Steel 11 11 Lead 5.7 10 Concrete 41 37 Steel 11 11 Lead 5. dsca is the distance from the radiation source to the patient.7 25 Concrete 49 46 Steel 11 11 Lead 5.7 5. for concrete(2. in cm2.7 5.566 d + 0.2005) End point energy (MV) Shield material T1 (cm) Te(cm) 6 Concrete 37 33 Steel 10 10 Lead 5. α is the scatter fraction defined at dsca. Radiation Exposure Control Table 3.7 5.9: Tenth value layers for primary barriers.7 5.7 Co-60 Concrete 21 21 Steel 7 7 Lead 4 4 When the collimator is rotated to 45 °. the above dimension become equal to its diagonal (56.35 g/cm3) Vs beam energies (NCRP 151. dsec is the distance from the patient to the point of interest.7 5. 53 F is the field area incident on the patient.87 g/ cm3) and lead (11. 7 12.15 0. which varies with scattering angle and beam quality. Table 3.13 7. in m. and beam energy. the energy of the scattered radiation will be degraded and the protection designed against leakage radiation should provide adequate protection against scattered radiation from the patient.05 3.4 20 80 11.353 135 0. α is the wall reflection coefficient. When the Primary Beam Strikes the Wall The barrier transmission factor (BW) needed to shield against scattered radiation when the primary beam strikes a wall is given by the following equation: Pdw 2 dr 2 BW = (20) αAWUT where dw is the distance from the radiation source to the scattering surface (wall). in m.25 3.73 7.370 0.233 150 0. .259 0.42 1.226 0. However. The use factor for the secondary barrier is unity.74 1.36 6.316 0. when the scatter angle is small. Textbook of Radiological Safety The α is the reflection coefficient of the barrier material.7 2.3 27.727 0.9 24. For large scatter angles. dr is the distance from the scattering surface (wall) to the point of interest.0 5. for a beam area of 400 cm2 incident at the scatter.37 90 0.97 3.212 Secondary Barrier for Scattered Radiation.3 11.5 10.7 30 6.8 16.1% of the incident radiation per 0. For small scatter angles (10°).10 gives the α values for different scattering angles.0178 for 24 MV X-rays and the scattered photons have energies close to that of the incident beam.1 m2 area irradiated.84 1. The required thickness is obtained from attenuation curves of the NCRB-51 report.10: The values of α for different scattering angles for Co-60 and 6MV beams (IAEA safety series 47) Scattering Co-60 (10-3) 6MV(10-3) 10MV(10-3) 18MV(10-3) 24MV(10-3) angle 10 11 16.488 0. the value of the scatter fraction a may be as high as 0. Radiation scattered by a patient or phantom is usually less than 0. Table 3.54 0. which is defined as the fractional scatter at 1m from the scatter. which depends on the wall material.06 60 2. It is the ratio of the scattered dose to the incident dose.21 45 3. patient scatter should not be ignored.328 0.714 0.2 1.375 0. 54 scattering angle.91 0. If the two thicknesses for leakage and scatter protection differ by more than one TVL use the greater thickness. In the plane of the patient. the leakage must not exceed an average of 0.5% of the primary beam. If the building has further floors above the bunker. thus allowing a greater design dose limit than if an office was placed directly above the bunker. and it would be reasonable to assume this value when determining the required secondary barrier thickness. Ceiling The roof section that can be struck directly by the radiation beam must be a primary barrier and the formulae used to determine the required thickness are the same as above. outside the useful beam at 1 m from the path of the electrons between the gun and target window and averaged over 100 cm2. manufacturers have protected their machines to better than 0. if the building is overlooked. use the larger thickness.1%.2% over a 2 m radius measured from the beam central axis. then 1000Pds 2 BL = (21) 55 WT . A storage room or plant room will have limited occupancy and access can be restricted. Radiation Exposure Control A is the field area projected on the scattering surface (wall). The photons scattered by the wall and by the patient are of about the same energy. If it is a single storey building. In general. If the thickness required to shield from patient scatter is different from that needed to shield from wall scatter by one TVL or more. If the thickness required to protect from leakage differs from that required to protect from scatter by less than one TVL. use the greater thickness and add one HVL of shielding material for the energy of the leakage radiation. However. then consideration should be given to locating a storage room or plant room immediately above the bunker (A plant room is used to house the chiller unit for the linear accelerator or heating and ventilation system plant). then the effect of skyshine must be considered which may result in the irradiation of nearby buildings. If there is a nuclear medicine department nearby. then the only consideration may be the limitation of access to the roof space. national and international protocols state that the leakage from the treatment head must not exceed 0.1% and a maximum of 0. use the larger thickness and add one- half value layer (HVL). then it should be noted that gamma cameras and possibly other imaging equipment are particularly sensitive to low levels of radiation that can affect certain patient investigations. The design dose limit for the roof will depend on the location of the bunker. otherwise. Secondary Barrier for Leakage Radiation For a linear accelerator. If BL is the transmission factor required to reduce the leakage dose to the permissible limit P. in m2. lead or steel are used as barrier materials. has 40 patients/day (8h) and the dose delivered per patient at the isocentre is 3 Gy. the transmission curves of the primary can be used for leakage radiation.0 2 56 .4-3. The physical properties of common shielding materials are given in Table 3. An optimally designed primary barrier will ensure adequate protection against scattered and leakage radiation. A number of different materials such as magnetite.4-3. workload. The dose rate at 1 m (DR0) = 0.8 × 60 = 48 Gy/h Workload = 40 × 3 × 5 = 600 Gy/week at the isocentre (at 80 cm) or 0.11: Physical properties of common shielding materials Shielding material Density. High density concrete (3.5 26 Low-carbon steel 7. whenever the machine is switched on and hence the use factor is unity (U=1). Calculate the DR0. and beam on time per day The dose rate at the isocentre = 0. which depends on structural and spatial considerations. it is commonly used as a barrier material to design walls and ceilings. Concrete.8 × (100/80)2 × 60 =75 Gy/h. The leakage radiation is present. Hence.35 11 High density concrete 3. Since concrete is relatively cheep. The quality of the leakage radiation is the same as primary. Textbook of Radiological Safety where dS is the distance from the isocentre to the area of interest for secondary barrier. the difference in barrier thickness is very small. whenever there is a scarcity of space. 1. Table 3. g/cm3 Atomic number Concrete 2. iron scrap and hematite may be mixed with concrete. The leakage radiation barrier thickness is always greater than scattered radiation.4 82 Worked Examples Example 7: A 60Co treatment facility. and the isocentric distance of the treatment unit (SAD) is 80 cm. The source specification is 0. the leakage is 0. In the case of mega voltage machine > 500 kVp.8 2 = 600 × = 384 Gy/week at 1 m.11. The facility is used for 5 days per week.90 26 Lead 11. which is equal to 1/1000. Since the use factor is unity the average position of the treatment head is taken to be at the isocentre so the distance ds is measured from the isocentre.8 Gy/min at 1 m.5 g/cc). In the case of low energy. lead and steel are recommended as barriers. since leakage radiation is more penetrating in nature. barites.1% through the source housing. Radiation Exposure Control The total dose delivered at the isocentre per day = 40 × 3 =120 Gy. Total beam-on time per day =120 × 75 = 1.6 h. Example 8: Calculate the primary barrier thickness by using weekly workload method and IDR (Assume effective dose limit as 20 mSv per year). P = 0.40 mSv /week,d= 3 m, W = 384 Gy /week at 1 m = 384 ×103 mGy/week SAD = 0.8 m, U=0.25, T=1 DR0 = 48 Gy /h = 48 × 106 μGy /h P ( d + SAD ) 0.4 ( 3 + 0.8 ) 2 2 B= = = 6.01 × 10 −5 WUT 384 × 10 × 0.25 × 1 3 Number of TVLs = log 10 [1/ (6.01 × 10-5)] = 4.22 The TVL for 60Co in concrete (density 2350 kg·m–3) is 218 mm and hence the required thickness for the primary barriers is (4.22 × 218) 920.2 mm. For this barrier thickness the IDR beyond the barrier is determined. Β × DR 0 6.01 × 10 −5 × 48 × 10 6 IDR = = = 199.7 μ Sv/h ( d + SAD ) ( 3 + 0.8 ) 2 2 Example 9: Calculate the primary barrier thickness by using weekly workload method (equation 14). (Assume P = 0.3 mSv/year as limit for design purposes). P = 0.3 mSv/50 week= 6 μSv/week d = 3 m, W= 384 Gy/week at 1 m SAD = 0.8 m U = 0.25, T=1 P ( d + SAD ) 6 × ( 3 + 0.8 ) 2 2 B= = = 9.03 × 10 −7 WUT 384 × 10 6 × 0.25 × 1 Number of TVLs = log 10 [1/ (9.03 × 10-7)] = 6.04 Therefore, a (6.04 ×218)1317 mm thick concrete primary barrier is required to shield a public area with an occupancy of 1. For a public area with occupancy factor of 0.5, a similar calculation gives the barrier thickness of 1252 mm. For a public area with an occupancy factor of 0.2, the barrier requirement is 1165 mm. 57 Textbook of Radiological Safety Example 10: For leakage radiation from the treatment head, the manufacturer’s specification should be used. There may be two values of leakage radiation quoted by the manufacturer, one when the source is in the safe position and one when the source is exposed for treatment; the larger value should be used in the shielding calculations. This value is usually less than the 0.1% (1/1000) of the primary radiation that is allowed. To determine the required barrier thickness, Eq.(21)is used. In this example: ds the distance from the isocentre to just outside the secondary barrier = 2.6 m P the design limit for a public area is 20 μSv/week (1mSv/50 week) T, the occupancy is 1. 1000 × 20 × 2.6 2 B= = 3.52 × 10 −4 384 × 10 6 × 1 Number of TVLs = log 10 [1/ (3.52 × 10–4 )] = 3.45 The thickness of concrete required is 3.45 × 218 = 752.1 mm DR 0 × B 48 × 10 6 × 3.52 × 10 −4 IDR = = = 2.49 μ Sv/h 1000 × dS 2 1000 × 2.6 2 Example 11: The barrier thickness necessary to shield against radiation scattered by the patient is determined from Eq. (19); P is 20 μSv/week dsca the isocentric distance is 0.8 m; dsec has the same value as dS in the previous calculation, 2.6 m; α the scatter fraction for 90 degree scatter is 0.0009 per 400 cm2 of area irradiated; F is the maximum field area incident on the patient (20 cm × 20 cm) =400 cm2 P × dsca 2 × dsec 2 BP = αWT × ( F / 400 ) 20 × 0.8 2 × 2.6 2 BP = = 2.5 × 10 −4 0.0009 × 384 × 10 6 × 1 × ( 400 / 400 ) Number of TVLs = log 10 [1/ (2.5 × 10–4 )] = 3.60 58 Radiation Exposure Control This is similar to the number of TVLs required to shield against leakage radiation. For 90 degree scatter the energy of the scattered radiation will be degraded and the protection designed for the leakage radiation should provide adequate protection against radiation scattered from the patient. Example 12: It is proposed to design a 6 MV linear accelerator facility for a work load of 1000 Gy /week at the isocentre. The location of a particular primary walls is at 3.6 m from the isocentre. Assume the use factor and occupancy factor are unity. The permissible limit (P) is 1 mSV per year= 1mSv / 50 week = 0.02 mSv/ week SAD = 1 m, d = 3.6 m W = 1000 Gy/week U = 1, T = 1 0.02 × 10 −3 ( 3.6 + 1) 2 B= = 0.423 × 10 −6 1000 × 1 × 1 Number of TVLs = log 10 [1/ (0.423 × 10–6 )] = 6.37 The actual thickness required (S) = T1 + (n – 1)Te = 0.37 + (6.37 – 1) × 0.33 = 2.14 m Since, the first TVL(T1) and subsequent TVL (Te) for 6MV is 0.37 and 0.33 m, from Table 3.9. Example 13: Find the width of a primary barrier, which is 3.6 m away from a 6 MV Linear accelerator. By using equation 18, W = 0.566 d + 0.61 = (0.566 × 3.6) + 0.61 = 2.03 + 0.61 = 2.64 m Facility Design for Brachytherapy To determine the required attenuation of the primary barriers, Eq. (14) is used. For brachytherapy the workload W is based on the dose delivered per treatment and the number of treatments: 59 W = RAKR × A × t × n (22) Textbook of Radiological Safety where RAKR is the reference air kerma rate for a source of unit activity; A is the total activity (activity per source × number of sources); t is the average duration of treatment in hours; n is the number of treatments per week. Using the AAPM Report 21 specifications, the workload may be represented by: W = Sk × t × n where Sk is the air kerma strength of the source in units of U or µGym2·h–1. Similarly, the dose rate D0 will be given by: D0 = RAKR × A (23) or, using the AAPM Report 21 specifications: D0 = Sk For brachytherapy the sources are not collimated so the use factor U will always be unity. A modified version of Eq. (14) for brachytherapy shielding may be written as: P × d2 P × d2 B= or B= (24) RADR × A × t × n × T Sk × t × n × T where P is the design limit; d is the distance, in m, from the exposed source position to the point of interest outside the barrier; T is the occupancy of the area outside the barrier. The RAKR values of different Brachytherapy sources are given in Table 3.12. Table 3.12: Physical data of Brachytherapy radionuclides Nuclide Mean photon Half-life RAKR (µGy energy(MeV) MBq-1 . m2 . h-1) Co-60 1.25 5.27 y 0.308 I-125 0.028 60.1 d 0.034 Cs-137 0.662 30.0 y 0.077 Ir-192 0.37 74.0 d 0.111 Au-198 0.42 64.7 h 0.056 Ra-226 0.78 1600 y 0.195 Unlike megavoltage bunkers, brachytherapy rooms are not used so regularly. Their use is often limited by the number of operating room sessions available for placing the source applicators in the patient. Consequently, basing the shielding design on an annual dose limit may result in high IDRs outside the barriers. This may necessitate these areas 60 being designated as controlled areas during the course of the treatment if Radiation Exposure Control the IDR exceeds 7.5 mSv·h–1. It is therefore recommended that the IDR be assessed (based on the maximum number of sources normally used) and also the maximum dose rate (based on the maximum number of sources available) before finalizing the shielding design. The Table 3.13, presents the minimum concrete thickness required to reduce the dose rate to 7.5 and 2.5 mSv/h at a distance of 3 m from the source. Table 3.13: Typical concrete barrier thickness required at 3 m from the radiation source Type Radionuclide Activity, Thickness (mm) to reduce GBq the dose rate to 7.5 µSv/h 2.5 µSv/h MDR afterloading Caesium-137 22.2 280 360 HDR after loading Iridium-192 370 440 510 HDR after loading Cobalt-60 185 680 770 Example 14: The Caesium manual after loader has 5 sources of each 100 mCi (3.7 GBq), to be used for gynaecological treatments. The reference air kerma rate (RAKR) for 137Cs is 0.077 μGy·MBq–1·m2·h–1.. The intended workload is 5 treatments per week. The shielding design will be based on the use of 5 sources per patient with a total activity of 18.5 GBq (0.5 Ci). The average treatment duration is 30 h to deliver an absorbed dose of 30 Gy to the prescription point. The weekly workload is obtained from Eq.(22): W = 0.077 × 18.5 × 103 × 30 × 5 = 2.13 × 105 μGy.m2 The design limit is 20 mSv /week for a public area (T=0.1) at 3.5 m from the treatment position of the sources. The required transmission through the barrier is determined from Eq. (24): 20 × 3.5 2 B= = 1.15 × 10 −2 2.13 × 10 5 × 0.1 The number of TVLs required is log 10[1/(1.15) × (10-2)] = 1.93. The TVL for caesium 137 for concrete is 175 mm and the total thickness of concrete required is 1.93 × 175 mm =337.7 mm. Example 15: A HDR Brachytherapy machine has 10 Ci (370 GBq) activity of Iridium -192 source, the average photon energy is 0.38 MeV and the RAKR is 0.111 mGy·MBq–1·m2·h–1.. The intended workload is 20 treatments per week. The shielding design will be based on the use of 10 Ci sources per patient with average treatment duration of 5 min (0.08 h), to deliver an absorbed dose of 8 Gy to the prescription point. The weekly workload is obtained from Eq. (22): W = 0.111 × 370 × 103 × 0.08 × 20 = 6.57 × 104 μGy.m2 61 Textbook of Radiological Safety The design limit is 20 μSv/week for a public area (T=0.1) at 3.5 m from the treatment position of the sources. The required transmission through the barrier is determined from Eq. (24): 20 × 3.5 2 B= = 3.7 × 10 −2 6.57 × 10 4 × 0.1 The number of TVLs required is log 10[1/(3.7 × 10-2)] = 1.43 The TVL for Iridium -192 for concrete is 152 mm and the total thickness of concrete required is 1.43 × 152 mm =217.3 mm. Example 16: The HDR unit contains 20 60Co sources each of 18.5 GBq (500 mCi). The reference air kerma rate (RAKR) for 60Co is 0.308 mGy·MBq– 1 ·m2·h–1. The intended workload is 30 treatments per week. Calculate the dose rate and the barrier thickness in concrete. The dose rate is calculated by using the equation 23; Do = 0.308 × 18.5 × 103 × 20 = 113,960 mGy·m2·h–1 To reduce the dose rate to the design limit is 7.5 mSvh–1 at 3.5 m (UK data) 7.5 ( 3.5 ) 2 B= = 8.1 × 10 −4 113 , 960 The number of TVLs required is log 10[1/(8.1 × 10-4)] = 3.09 The TVL for Cobalt -60 for concrete is 218 mm and the total thickness of concrete required is 3.09 × 218 mm =673.6 mm. BIBLIOGRAPHY 1. AERB safety code: Brachytherapy sources equipment and installations. SC/ MED-3. 1988. 2. AERB safety code: Medical diagnostic X-ray equipment and installations. SC/MED-2(Rev.1)2001. 3. AERB safety code:Telegamma therapy equipment and installations. SC/MED- 1.1986. 4. FM Khan. The Physics of Radiation therapy, (3rd edn.) Lippincott Williams & Wilkins 2003. 5. Jerrold TB, Seiber JA, Edwin ML, John MB. The essential physics of medical imaging, (2nd edn.), Lippincott Williams & Wilkins 2002. 6. NCRP. Medical X-ray, electron beam and gamma ray protection for energies up to 50 MeV. Report No. 102. Bethesda, MD: National Council on Radiation Protection and Measurements, 1989. 7. NCRP. Radiation protection design guidelines for 0.1-100 MeV particle accelerators facilities. Report No.51. Washington DC: National Council on Radiation Protection and Measurements,1977. 62 Radiation Exposure Control 8. NCRP report 151.Structural Shielding Design and Evaluation for Megavoltage X- and Gamma-Ray Radiotherapy Facilities. National Council on Radiation Protection and Measurements 7910 Woodmont Avenue, Suite 400/Bethesda, MD 20814-3095. 9. NCRP. Structural shielding design and evaluation for medical use of X-rays and gamma rays of energies up to 10MeV. Report no.49. Washington,DC: National Council on Radiation Protection and Measurements, 1976. 10. Patton HM. Shielding Techniques for radiation oncology facilities, (2nd edn.) Medical physics publishing. www.medical physics.org 2002. 11. Radiation protection in the design of radiotherapy facilities, Safety reports series No. 47. International Atomic Energy agency Vienna, 2006. 63 Chapter 4 Planning of Radiological Facility GENERAL GUIDELINES While planning a radiation facility, consideration should be given to radiation safety, economy and convenience. The following features are very important while planning a radiation installation either it is diagnostic radiology or Nuclear medicine or Radiotherapy facility. 1. Location: The site or room should be located as far away as feasible from areas of high occupancy and general traffic, such as maternity and pediatric wards and other departments of the hospital that are not directly related to radiation and its use. It should be preferably at the extreme end of the hospital and be easily accessible to various departments of the hospital. 2. Layout: The layout of rooms should aim at providing integrated facilities so that handling of radiation equipments and related operations can be conveniently performed with adequate protection. The installation should permit safe and easy transport of equipments and nonambulatory patients. 3. Room size: The room must be spacious enough to permit the radiation equipment and accessories, use and servicing of the equipment with safety and convenience. It should facilitate the wheeling in of patients in and around the couch of the unit. Proper grouping of the rooms comprising the installation should be done bearing in mind their dependence on each other. 4. Shielding: Appropriate structural shielding shall be provided for the walls, ceiling, floor, doors and windows, so that the doses received by the occupational workers and members of the public are kept to a minimum and shall not exceed the annual effective doses as prescribed by the competent authority. The current limits are 30 mSv and 1 mSv for the workers and the members of the public. 5. Doors: The number of doors for entry and windows should be kept minimum. It should permit safe and easy transport of equipment and nonambulatory patients. The doors shall provide the same shielding as that of the adjacent walls, in case persons are likely to be present in front of them, when the machine is energized. 6. Openings and ventilation: Unshielded openings, if provided in the room for ventilation or natural light must be located above a height of 2 m from the ground or finished floor level outside the room. Planning of Radiological Facility 7. Equipment layout: The radiation equipment must be installed in such a way that in normal use the useful beam is not directed towards control panel, doors, windows, dark room and areas of high occupancy. The useful beam should preferably be directed towards unoccupied areas. Sufficient area should be left all around the couch for safe and free movements of equipment/ trolley, staff and service personnel. 8. Interlock: Suitable electrical interlocks between door, equipment and control panel must be provided, wherever it is necessary. 9. Warning light and placard: A suitable warning signal such as the red light must be provided at a conspicuous place outside the room and kept ON when the unit is in use, to prevent entry of persons not connected with the examination or treatment. An appropriate warning placard must also be posted outside the room entrance or door. 10. Air conditioning: The treatment room may be airconditioned to control temperature, pressure and humidity. It will ensure long-term, trouble free, safe operation of the equipment. Spilt AC with sufficient capacity to suit the room size is preferable than window AC’s. 11. Waiting area: In order to avoid the crowding of patients and relatives near the entrance door, waiting area must be provided outside and adjacent to the equipment room. It should have sufficient area to match the patient workload with toilet facility. 12. Emergency and trolly bay: There should be exclusive room for handling emergency. In addition, space must be provided to accommodate trolly and wheel chairs etc. ESTABLISHING A DIAGNOSTIC X-RAY FACILITY 1. Room size: The room housing an X-ray unit shall be not less than 18 m2 for general purpose radiography and conventional fluoroscopy equipment. The size of the room housing the gantry of the CT unit shall not be less than 25 m2. Also, not more than one unit of any type shall be installed in the same room, and no single dimension of these X-ray rooms shall be less than 4 m. In the case of mammography, the room size shall be not less than 10 m2, and no single dimension of the room shall be less than 3 m. A typical layout for a diagnostic X-ray department is shown in Fig. 4.1. 2. Wall thickness: If the X-ray installation is located in a residential complex, it shall be ensured that i. Walls of the X-ray rooms on which primary X-ray beam falls is (are) not less than 35 cm or 14 inch thick brick or equivalent, ii. Walls(s) of the X-ray room on which scattered X-ray fall is (are) not less than 23 cm or 9 inch thick brick or equivalent, and iii.There is a shielding equivalent to at least 23 cm or 9 inch thick brick or 1.7 mm lead in front of the door(s) and windows of the X-ray room to protect the adjacent areas, either by general public 65 5 cm.5 mm lead equivalence. inside a stationery /mobile protective barrier. Appropriate shielding must be provided for the dark room to ensure that undeveloped X-ray films 66 Fig.35 g/cc). iv.5 mm). The density of the normal masonary brick is considered as 1.6 g/cc. Dark room: The dark room should be located in such a way that the primary beam is not directed on it. Control room: For equipment operating at 125 kV or above.1: A Typical layout of a diagnostic X-ray department . not less than 6 inch or 13. Doors: Doors to be lined with 1. direct viewing (1. 7.The ceiling must have a thickness of concrete (density 2. Mobile protective barrier: Control panel should be kept behind the mobile protective barrier (MBP) of thickness 1. 4. The protective barrier should have sufficient lead equivalence (1. Textbook of Radiological Safety or not under possession of the owner of the X-ray room.5 mm thick lead equivalents.5 mm thick lead sheet with proper overlapping at the joint and junction and wall of 9 inch thickness of brick and ceiling of 6 inch of concrete. 3. 4. the control panel must be installed in a separate control room located outside but contiguous to the machine room and provided with appropriate shielding. 6.5 mm lead equivalence) and oral communication facilities between the operator and the patient. The X-ray units operating below 125 kVp in diagnostic radiology are exempted from the above class and may be located away from the primary beam. Both control console and machine can be housed in the same room. Viewing window: Lead glass of suitable dimensions are provided as viewing windows of 1. 5. 8. and employees who do not work routinely with or around radiation sources. visitors to the facility. Mobile units does not require plan approval unless they are used as fixed units. Approval: Two copies of the X-ray room layout drawn to scale 1:50. such as X-ray procedure rooms and X-ray control booths or other areas that require control of access.2: X-radiation warning sign 67 . are to be sent for approval to Head. AERB. Anusaktinagar. Uncontrolled areas are those occupied by individuals such as patients. these areas are usually in the immediate areas where X-ray equipment is used.2. Areas adjacent to but not part of the X-ray facility are also uncontrolled areas. payable in Mumbai. 4. Planning of Radiological Facility stored in it will not be exposed to more than an air kerma rate of 10 μGy per week. Radiological Safety Division. Atomic Energy Regulatory Board. Niyamak Bhavan. towards charges for approval of the layout. occupancy and working conditions are controlled for radiation protection purposes. The workers in these areas are primarily radiologists and radiographers who are specifically trained in the use of ionizing radiation and whose radiation exposure is usually individually monitored. This implies that access. occupancy and working conditions for radiation protection purposes. Placard: A warning placard as shown in the Fig. Uncontrolled areas for radiation protection purposes are all other areas in the hospital or clinic and the surrounding environment. In facilities that use X-rays for medical imaging. Mumbai-400094 from radiation safety point and along with a required fee in the form of demand draft for an appropriate amount. Fig. 4. Controlled and Uncontrolled Areas A controlled area is a limited access area in which the occupational exposure of personnel to radiation is under the supervision of an individual in charge of radiation protection. drawn in favour of pay and accounts officer. 9. must be posted outside the room entrance or door. It should not be used as primary barrier.5 mm lead equivalence W: Window or ventilator at a height of 2.3: Model plan for a general radiography room FLUOROSCOPY INSTALLATION Fluoroscopic imaging systems are usually operated at potentials ranging from 60 to 120 kVp. Objects that are irradiated are considered as primary barriers. D: Entrance door lead lined with 1. The operator should be in the control area.5 mm lead equivalence V W: Viewing window of 1. Textbook of Radiological Safety GENERAL RADIOGRAPHY INSTALLATION These X-ray units are operated in the range of 50-150 kVp applied voltage. The viewing window at the control barrier must be 45 × 45 cm size and centered.0 mm of lead sheet with proper overlapping at all the joints. Additional shielding must be provided for the wall behind the chest stand.0 m from the finished floor level outside the X-ray room. Therefore. Fig. (Not to scale) MPB: Mobile Protective Barrier of 1. Provisions are made to observe and communicate with the patient on the table.1 m height. a protective design for a room containing only .m. 4. 4. The shield at the control (protective barrier) must be a permanent /mobile one with 2. A typical model plan is shown in the Fig. A primary barrier is incorporated into the fluoroscopic 68 image receptor. Walls of minimum 23 cm thick brick and ceiling 15 cm concrete.3 Area: 18 sq. 4. 4.5 sq.5mm of lead sheet with proper overlapping at all the joints and junctions. Area: 7.4. Doors need special attention as they offer poor attenuation than Brick or gypsum wall board. 4.m. A typical model plan is shown in the Fig. consider only secondary protective barriers against leakage and scattered radiations. The walls are constructed with bricks or gypsum wall board. higher thickness of gypsum wall board is recommended than that calculated.5 mm lead equivalence W: Window or ventilator at a height of 2. Gypsum wall board may contain voids and non uniform areas. However. A typical model plan is shown in the Fig. Adequate protective barrier of lead acrylic or lead glass are incorporated into dedicated mammography units. Planning of Radiological Facility a fluoroscopic unit. MAMMOGRAPHY INSTALLATION Mammography units are typically operated between 25-30 kVp. Most modern fluoroscopic X-ray imaging systems also include a radiographic X-ray tube. Fig.5. (not to scale) V W: Viewing window of 1. Walls of minimum 23 cm thick brick and ceiling 15 cm concrete. Hence. The shielding requirements for such a room are based on the combined workload of both units.0 m from the finished floor level outside the x-ray room D: Entrance door lead lined with 1. provisions are made with primary barriers so that the function of the room can be changed at a later date without the need to add additional shielding.5 × 5 =37.4: A typical layout of a fluoroscopy installation 69 . walls and ceilings need special consideration. Walls of minimum 23 cm thick brick and ceiling 15 cm concrete.5 =52. The radiation levels in the direction of the gantry are much less than the radiation levels along the axis of the patient table. Due to the potential for a large amount of secondary radiation.0 m from the finished floor level outside the X-ray room. COMPUTED TOMOGRAPHY INSTALLATION Computed tomography (CT) employs a collimated X-ray fan-beam that is intercepted by the patient and by the detector array.5 mm lead equivalence . floors.6. (not to scale) 70 V W: Viewing window of 1. Area: 7 × 7. 4. typically in the range of 80 to 140 kVp.m. only secondary radiation is incident on protective barriers. Additionally.5: Model plan for a mammography room Area: 3 × 5.0 mm of lead sheet with proper overlapping at all the joints. D: Entrance door lead lined with 1. Textbook of Radiological Safety Fig. 4. Consequently. A typical model plan is shown in the Fig.5 sq.m (Not to scale) W: Window or ventilator at a height of 2. as well as the workload are much higher than for general radiography or fluoroscopy. scattered and leakage radiations from CT systems are not isotropic. The operating potential.5 =16.5 sq. 2.5mm of lead sheet with proper overlapping at all the joints and junctions. . Hot labs and radioactive storage areas should be located away from other busy work areas. ESTABLISHING A NUCLEAR MEDICINE FACILITY General Guidelines 1. 4. Walls of minimum 23 cm thick brick and ceiling 15 cm concrete. 3. It shall be located away from high patient or public occupancy areas and sources of intense radiation. Location: The installation should be located in a relatively unfrequented part of the building so that access to the area can be easily controlled. Areas of high activity and contamination shall be demarcated by physical barriers. radiation levels can be effectively maintained with permissible limits in the immediate vicinity. The location of the installation or the facilities provided be such that the possibilities for spread of both surface and air-borne contamination are minimal.6: Model plan for a computed tomography room W: Window or ventilator at a height of 2. public corridors. secretarial offices and away from imaging and low level counting rooms. The location should be chosen that the minimum expenditure on shielding. Fire hazard potential should be minimum in the area chosen.0 m from the finished floor level outside the X-ray room D: Entrance door lead lined with 1. Active areas shall be arranged in increasing order of 71 the activity with entrance from lowest active area. Planning of Radiological Facility Fig. The laboratory design should permit separate storage of glassware and work tools (tongs. Warning light and placard: A suitable warning signal such as the red light must be provided at a conspicuous place outside the room and kept ON when the unit is in use. Air conditioning is essential to maintain a clean. dust free and dry environment for electronic instruments that are sensitive to heat and moisture changes. 11. causing corrosion as well as current leakage.7: Placard for storage radiation and containers rooms 13. 9. 10. high humidity is bad for electronic components. Instruments must be housed in an air conditioned environment. 6. 4. Ventilation system shall be of once-through type with unidirectional air flow from areas of lower activity to higher activity. The exhaust from fume hoods shall be let out directly into the open after filtering. Fig.7A) . Drain pipes and delay tank shall be leak proof and corrosion –resistant. Work surfaces shall be covered with nonporous and non reactive material. Work benches should be sufficiently sturdy to support lead shielding.7B). An appropriate warning placard must also be posted outside the room entrance or door (Fig. 4. Storage containers shall be posted with a different placard (Fig. 12. floor and doors of the active areas shall have hard. stirring devices) not used with radioactive materials to prevent needless contamination or mixture with similar items used with radioactive preparations. Running hot and cold water must be available. 5. and a dehumidifier may be needed to maintain humidity at about 50%. Plumbing shall provide direct flow of liquid effluents from active areas either directly to the delay tank or to the ultimate discharge point. It is desirable that the sinks in hot labs have foot or elbow operated taps. nonporous and leak proof covering. Wash basins and sinks should be conveniently available where unsealed radioactive materials are handled. 7. 4. Planning and approval of nuclear medicine laboratory: Two copies of the layout of the nuclear medicine laboratory (drawn to scale 1:50) 72 . Textbook of Radiological Safety 4. to prevent entry of persons not connected with the examination or treatment. Walls. 8. washable. consideration was given to the categories of nuclear medicine ranging from simple imaging or in vitro laboratories to more complex departments. cover receptionist and secretarial needs. windows. along with fume hoods. A single imaging room connected to a shared reporting room should be sufficient. Anus akti Nagar. training programs. Niyamak Bhavan. Level 2 This level is appropriate for a general hospital where there are multiple imaging rooms in which in vitro and other nonimaging studies would generally be performed as well as radionuclide therapy. physics and radiation protection services are contracted outside the centre. A site plan (drawn to scale 1:500) indicating the location of the nuclear medicine laboratory and the occupancies around it including those above the ceiling and below the floor. Planning of Radiological Facility indicating the various rooms along with their dimensions. Radionuclide therapy for inpatients and outpatients is provided. such as radiology. AERB. This level is appropriate for a private practice. radionuclide therapy and nonimaging in vitro tests including RIA’s. workbenches. Level 3 This level is appropriate for an academic institution where there is a need for a comprehensive clinical nuclear medicine service. Now a days all assays (radioassays or enzyme linked immunosorbent assays (ELISAs) are done in biochemistry laboratories. Categorization In the past. if any. These departments also involved in advanced clinical services. performing a full range of in vitro and in vivo procedures. with backup. whereas nuclear medicine departments are involved largely in diagnostic procedures. Mumbai-400 094. Radiological safety division. The level of nuclear medicine services is categorized according to three levels of need: Level 1 This level is appropriate where only one gamma camera is needed for imaging purposes. The radiopharmaceutical supply. human resource development and research program. positions of doors. sinks and other details should be sent to the Head. should also be sent to AERB. Other services. 73 . with a staff of one nuclear medicine physician and one technologist. research and development. exhausts. rooms should have double glazed and insulated windows to avoid the buildup of dust. Floors should be impervious to liquids. 2. All rooms should have their own 74 separate power supply and stabilizers and be equipped with hand . but preferably larger. Ventilated fume cupboards are desirable. Imaging Rooms Imaging rooms should be at least as large as given in the manufacturer’s recommendations. A portable contamination monitor (acoustic dose-rate meter) and/or a survey meter to monitor beta and gamma contamination. dynamic and preferably SPECT studies with its various clinically proven acquisition and processing protocols.). 4. 5. Rectilinear scanners are no longer appropriate. 5. An isotope dose calibrator. 2. Walls and doors of laboratories should be painted with good quality washable paint. including a pinhole collimator. 6. etc. Tight fitting oversize doors and efficient heating. air conditioning and humidity control units are also required. 3. A collimated scintillation probe and counting system for uptake measurements of thyroid function and other in vitro and diagnostic studies. to accommodate patients on stretchers. minimum requirements are as follows: 1. Textbook of Radiological Safety IN-VIVO DIAGNOSTIC FACILITY Introduction An in-vivo diagnostic facility need optimal space. Work table tops should have a smooth laminated finish. equipment and manpower. it should have its own computer for static. The design and planning should address many factors including radiation safety. Provision must be made for a reasonable range of collimators (low energy general purpose. Equipment While the capacity and quantity of individual pieces of equipment needed depend on the volume of the service. There should be an adequate supply of lead containers and shielding lead bricks. In some hospitals. The following are very important on radiation safety point of view: 1. If only one gamma camera is funded. Remote handling devices are desirable. high energy. 4. A gamma camera with computer and appropriate clinically proven software. 3. A larger area provides a more pleasant working environment and reduces the risk of radiation to staff. Fig. An intercom and/or telephone are important for facilitating communication.8 and a typical plan of a radioisotope is shown in Fig. Premises should generally provide working conditions that are hygienic and spacious. 4. 4.8: A typical floor plan of a nuclear medicine department IN-VITRO AND RADIOIMMUNOASSAY (RIA) The design and structure of the building can affect the quality of an RIA centre. It is essential to reserve an area for record keeping and the sorting 75 and labeling of samples. . resuscitation trolley and other special facilities. A patient reception area with a waiting room and an area for taking blood samples should be available. 4. Planning of Radiological Facility washbasins with hot and cold running water. The reception area should be equipped with a couch. A typical floor plan of a nuclear medicine facility is shown in the Fig.9. A separate washbasin. 4. labelled to this effect. Types of RIA Laboratories RIA laboratories are graded on the basis of nature and scope of activity. solvents. The areas designated for assays are separated from those reserved for other activities such as patient reception.9: Typical plan of a radioisotope laboratory Floors and bench tops should be smooth and of nonabsorbent material to facilitate cleaning and decontamination in the event of chemical or radioactive spillage. as well as a refrigerator in which to store stock solutions of radioactive material. fraction collector and/or high performance liquid chromatography (HPLC) system. test tubes and other consumables is provided. with its use prohibited for any other purpose. A storage room for buffer chemicals. A 76 Grade 1 laboratory is a basic one using reagents. should be reserved for the washing of hands of laboratory personnel. whether obtained in bulk . A laboratory preparing its own tracers using imported 125I sodium iodide would need a ‘hot’ laboratory with sufficient space to accommodate a fume cupboard. Textbook of Radiological Safety Fig. record keeping and computing. used RIA tubes and reusable pipette tips should have one or two large sinks and a drying oven. Sinks should be conveniently located at each workbench. The washing-up area for glassware. These areas will need suitable shielding and. patient waiting areas and offices. in addition to all of the above activities. laboratories should be lockable. from an outside source. Storage areas will be necessary for radioactive materials as well as for nonradioactive components used in radiopharmaceutical preparation. All surfaces of the radiopharmacy. at least for selected procedures. Since. A Grade 2 laboratory would similarly use primary reagents obtained from elsewhere but in addition produce its own tracers. a refrigerator and freezer may also be required. benches. 4. impervious and non- absorbent. also produces polyclonal antibodies falls into Grade 3. are classified as Group 4. A typical radiopharmacy layout is shown in Fig. It should be away from gamma cameras. floors. It is also important to consider whether there are working areas above or below the radiopharmacy laboratory. In addition. and for security reasons.10. with minimal production of reagents confined to standards and quality control material for the simpler analytes. 4. A Grade 3 laboratory could serve as a national or regional reagent production and distribution centre.10: A basic radiopharmacy facility 77 . Fig. The access to the radiopharmacy should be restricted. Floor surfaces and benches should be continuous and coved to the wall to prevent accumulation of dirt or contamination. tables and seats should be smooth. depending on the type of product being prepared. walls. radiopharmacies will be handling unsealed sources of radioactivity. Planning of Radiological Facility or as commercial kits.g. monoclonal antibody production centers. to allow for easy cleaning and decontamination. The radiopharmacy needs to be equipped with at least one isotope calibrator so that all activity can be measured accurately. contamination monitors will be required to check for any radioactivity that may have been spilt. A centre that. in order to avoid unnecessary radiation exposure to people working in those areas. Finally. Radiopharmacy The layout of the department should enable an orderly flow of work and avoid the unnecessary carriage of radioactive materials within the department. using 125I produced elsewhere in the country or obtained from abroad. if they are also engaged in RIA. a reference source (e. 137Cs) will be necessary to ensure continuing reliability of the calibrator. or organize and operate an External Quality Assurance Services (EQAS). Flooring should be free of open joints and sealed to the walls. and all precautions must be taken to avoid unnecessary exposure to radiation. Radionuclides must be used in strict accordance with safety measures and any special instructions. with dedicated bathroom and toilet. a regular inspection of work in progress is advisable to ensure adherence to agreed plans and specifications. If any building work is to be performed. agreement should be reached on medical and radiation safety 78 protocols. visitors and the general public. b. Brick walls often have inadequate mortar joints. c. Before commencing therapy. Licensing The administration of therapeutic doses of radionuclides must be under the responsibility of a physician who is licensed under AERB regulations to administer radioactive materials to humans. Patients must be housed in a separate room. Facility design and construction When designing therapy units. It is both easier and less costly to design a unit correctly from the start than to modify it later. . it should be noted that: i. Access to the treatment room must be controllable. as well as health workers and the environment. it may be necessary to determine experimentally the adequacy of walls and floors as radiation shields. The following steps are to be taken before commencing therapy procedures. If an existing space is to be modified. Close cooperation between the nuclear medicine staff and architects and builders is vital. physicists and nurses may also be subjected to licensing. Textbook of Radiological Safety RADIONUCLIDE THERAPY Introduction The therapeutic use of radionuclides may be a potential radiation risk for both family members and individuals close to the patient. ii. Responsibilities The physician administering the therapeutic radionuclide dose is ultimately responsible for taking every precaution to avoid unnecessary radiation to staff. Technical staff. it is important to bear in mind the following: a. Any required shielding must be designed for the proposed floor plan in the eventuality of pregnant patients in adjacent rooms. Radioactive material for diagnosis or therapy should only be used and stored at medical institutions which possess regulatory license. other patients. a fact often forgotten by builders. which can be a shielding problem. In particular. Access Access to the room for the delivery and replacement of the treatment unit must be considered. Also. This dosimetry duct should always be through a secondary barrier so that the primary beam can never strike it. may be more important than construction cost. A little effort devoted to familiarization and training in the medical and safety aspects of radionuclide therapy can avoid potentially serious problems later. radiotherapy facilities using radioactive sources should be located in areas where access by members of the public to the rooms where sources are used and stored can be restricted. As pointed out in NCRP 49. and consolidation of all therapeutic radiological services. Patients may arrive in wheelchairs or on trolleys or beds. with room for an operator to walk around it. and the administration date. the reduction in shielding costs for floors and outside walls should be weighed against the expense of excavation. the radiopharmaceutical and radioactive quantities administered. watertight sealing and of providing access. Planning of Radiological Facility Records A record keeping system must be in place before treatment commences. For rooms below ground level. Proximity to adjunct facilities. In addition to normal medical records. as well as provision for future expansion and/or increased workload. the proximity of source storage facilities to personnel that may respond in the event of a security breach should also be considered. Training Radionuclide therapy may involve staff outside the nuclear medicine department. Ideally it should run at an angle through the barrier to the treatment control area. should be considered when locating a therapy installation. The desirable . for security purposes. a logbook should be kept. It is necessary to include in the room design an open access conduit for dosimetry equipment cables. Entrance to the room may be through a shielded door or via a maze. listing the patient’s name. ready access for in- patients and outpatients. initial cost. ESTABLISHING A RADIOTHERAPY FACILITY Location Radiotherapy departments are usually located on the periphery of the hospital complex to avoid radiation protection problems arising from therapy rooms being adjacent to high occupancy areas. Further. however. especially nurses and medical staff. Room Size The room should be large enough to allow full extension of the couch in 79 any direction. operational efficiency. The radiation output of the device should not be resumed automatically after the door is closed again. A motorized door must have a manual means of opening the door in the event of a power or mechanical failure. gates. it is recommended that a physical barrier such as a normal door(s) or gate be installed to discourage entry to the maze during patient treatment. All doors. a motorized door may be necessary. there may be no need for a radiation protection door at the maze entrance. . If a shielded barrier is required to reduce dose rates. photoelectric beams and motion detectors must be interlocked to the treatment unit to prevent an exposure if a door is open. breast positioning boards. There should also be an emergency means by which the motion of the door is stopped. a restricted access passage way leading to the room may be incorporated in the design. etc. The interlock must also ensure that when the door is opened the irradiation will be terminated. a total body irradiation (TBI) procedure will require a larger treatment distance to one wall. Additionally. and should be located to minimize the walking distance for each patient set-up. the room may need to be larger. any motorized door that is too heavy to be stopped manually should have sensors that stop the motion of the door to prevent injury to personnel and patients. Another advantage of a maze is a route for ventilation ducts and electrical conduits without compromising the shielding. For intraoperative procedures (IORT) that require extensive support staff and equipment. Linear accelerators usually require a gate to prohibit entry during treatment times and /or motion detectors to detect unauthorized entry. The accessory equipment such as electron applicators. Textbook of Radiological Safety size depends upon the type of treatments. if a shielded door is not required to reduce dose rates. Ideally this should be long in length and small in width. The minimum width may be determined by the dimensions of the treatment unit to be delivered by this route or by access for a hospital bed. or if there are enough bends. However. If the length of the maze is sufficient. Maze In order to reduce the radiation dose near the entrance. Doors and Interlocks The treatment room is a controlled area and a barrier be installed at the entrance to the maze or treatment room to restrict access during exposures. This passage way is termed as the maze. for example. are usually stored within the room. A maze ensures the exit of the photon radiation after sufficient scattering. The interlock should be fail- safe so that safety is not jeopardized in the event of failure of any one 80 component of the system. A maze reduces the need for a heavy shielding door. a barrier that restricts access to the treatment room outside normal working hours may also meet certain specifications. Only after activation of the reset switch can the radiation be turned on. this switch should have a delayed action to allow the person time to leave the room and maze after resetting the switch. There may be computer terminals for record and verification. There should also be provision for two way audio communication between the treatment control area and the room. If these devices indicate the potential presence of an unauthorized person. This switch should be connected in series with a second switch just outside the door. a video camera that provides continuous remote surveillance of the device. electronic portal imaging. To achieve this. In facilities using radioactive sources. consistent with tele-zoom capabilities. Treatment Control Area The treatment control area is where the operators control the machine. There should be clear access to any dosimetry ducts. closing the door may activate the second switch. A patient activated alarm may be required for patients unable to give an audible call. an alarm should indicate this locally and remotely so that personnel can respond in a timely fashion. a photoelectric beam or motion detector system installed in the maze and/or treatment room. 81 . Planning of Radiological Facility In certain centers. These should be situated 15° off and above the gantry rotation axis for optimum observation of the patient on the treatment couch. This area should be close to the entrance to the treatment bunker so that the operators can view the entrance area. The control area should be sufficiently large to accommodate the treatment unit control console and associated equipment. or a door interlock can be incorporated. as well as closed circuit TV monitors for patient observation. Only after activation of both switches can the radiation be turned on (IPEM Report 75). Two cameras are recommended. hospital information system and dosimetry equipment. If there is a maze. Patient Observation and Communication The operator should be able to visually monitor the patient during treatment with closed circuit TV. An unauthorized access to the source can be detected in a timely fashion. to minimize degradation of the image receptor by scatter radiation. it is advised that a door-reset switch be situated near the exit from the treatment room at the position where the person leaving the room has a clear view of the room. These technical measures will be independent of any interlocks that terminate the radiation beam during normal operation because they will not be operational when the treatment unit is powered off outside operational times. The cameras should be located far away from the radiation source. In cases where the door is clearly visible from the control panel. The same person should operate both switches. heating and ventilation ducts. For higher 82 energies. It is recommended that ducts should only penetrate the treatment room through secondary barriers. The recommended placement of these ducts is above a false ceiling along the path of the maze. less shielding material is needed as shown in Fig. Treatment machine cables are usually run below the floor level under the primary or secondary barriers. If required. The shielding must be evaluated carefully if the ducts must penetrate the primary barrier. the cross-section of the duct should have a high aspect ratio to decrease the radiation passing through the duct as a result of multiple scattering interactions with the duct/shielding walls. lead or steel plates are suitable materials to compensate for the displaced shielding. The ducts should be placed in such a way that radiation passing through them will require the least amount of compensation for the barrier material it displaces. to exit the maze at or near the external maze door where the photon and/ or neutron fluence are lowest. additional shielding is not usually required unless the treatment control area is directly behind a primary barrier. It could either run at an angle through the barrier or have one or more bends in it so that the total length of the duct is greater than the thickness of the radiation barrier. usually no additional shielding around the duct is required. but follow the maze to exit the treatment room as described above or follow a route beneath the shielding barrier. an additional shielding is required. It is recommended that they also should not penetrate through barriers. which makes it costly to compensate for the shielding material they displace. For accelerators of energies up to 10 MV. No duct with a diameter greater than 30 mm should penetrate the primary shielding. ducts for physics equipment and other service ducts. The amount of additional shielding required to shield penetrations in shielding walls depends on the energy of the radiation beam. Water pipes and narrow electrical conduits are usually placed in groups inside a larger duct. and the cable passes beneath the same primary barrier. the room layout and the route of the duct(s).11. If the ducts must pass through a secondary barrier. The axis of the duct and the longer side of the duct cross-section should be as orthogonal as possible to the direction of the leakage radiation from the target towards the duct. before bending up to reach the treatment control area. Provided there are no rooms below. 4. Textbook of Radiological Safety Ducts and Shielding Ducts and conduits between the treatment room and the outside must be adequately shielded. it is better to place the additional shielding outside the treatment room. To shield the scattered radiation that passes along the duct. where the radiation has a lower average energy and therefore. Heating and ventilation ducts should not penetrate through primary barriers because of their large cross-sectional area. This includes ducts for cables necessary to control the treatment unit. No duct should run orthogonally through a radiation barrier. If it is necessary for the ducts . The conduits are usually PVC pipes of 80 to 100 mm diameter included in the concrete formwork. The main room lighting can be fluorescent lights that extinguish when the field light is turned on and the incandescent room lights are used for the dim level. it is recommended that incandescent lights be used for the dim level. They should be inclined at an angle (20 to 45 degree. Conduits as described above usually do not need additional shielding unless the barrier is constructed of material with a much higher density than 2350 kgm–3. and in vivo dosimetry equipment cables. and penetrate through the secondary barrier but not through the primary barrier. If the openings are at least 300 mm above floor level they are more convenient to use. and the alignment lasers should also be switched on. Room Lighting and Lasers To set up a patient for radiotherapy treatment. they should be placed as high as possible to minimize the scattered radiation to personnel outside the room.11: A bend in duck to avoid radiation streaming to pass through the secondary barrier. When the field light is switched on the room lights should dim to a pre-set (but variable) level. Ideally. the room lights should be dimmable so that the field light of the treatment unit and the alignment lasers can be seen easily. in the vertical and horizontal planes). Planning of Radiological Facility Fig. 4. the opening in the treatment control area should be at the counter top level and the opening in the treatment room side should be at a different level but within easy reach. quality assurance (QA) equipment cables. When the field 83 . Conduit Conduits are required for dosimetry cables. Since fluorescent lights do not dim very satisfactorily. It is useful to be able to control the room lights and lasers from the treatment unit control pendant in the treatment bunker. beam data acquisition system control cables. Construction Materials To house radiation treatment facilities. The laser switching should be controlled from the hand pendant. Depending on the occupancy of the adjacent area. Four alignment lasers are recommended in total. Inc Clay bricks 1600 ⎫ May be used for installations up to ⎬ Breeze blocks 1100-1400 ⎭ 500 kV with supplementary lead or steel shielding Earth fill 1600 May be useful in bunker which is below ground level Steel 7900 Normally used as supplementary Lead (solid) 11340 Shielding on an existing treatment room Concrete is normally specified by strength. Karzmark et al. recommend that if junction boxes or alignment lasers are to be inset in the walls. concrete will usually be the material of choice since it is the least expensive. The dimmable lights may remain on at all times. Table 4. then the voids need to be backed with 40 mm thick steel plate with a 30 mm margin all around. and one mounted in the ceiling directly above the isocentre. Compton absorption dominates and the shielding material will absorb the radiation according to the density of material.1 lists a range of typical building materials with their densities. especially in a secondary barrier. Strength is increased by increasing the proportion . The fourth laser should project a sagittal line along the gantry axis. with density being of 84 secondary importance. if space is at a premium it may be necessary to use a higher density building material. the main room lighting is switched on and the lasers switched off. Three lasers projecting a cross: two aligned with the gantry positions of 90° and 270°.m-3) Comment Concrete 2350 Will vary with mineral content Barytes concrete 3400-3500 Most commonly used for dense concrete but expensive Iron ore with ferrosilicone 4000-5400 Range of densities which depend on proportions of ore mixture to sand Ledite 3844 and 4613 Pre-moulded high density inter- locking blocks from atomic inter- national. Table 4. Concrete density will vary according to the aggregate used. but it is also useful to be able to switch them off independently for QA tests. Textbook of Radiological Safety light is switched off. This laser is usually mounted on an angled bracket on the wall opposite the gantry. it may be acceptable to have a reduction in the shielding over a small area. For therapy installations operating over 500 kV. Most published data assume a density for concrete of 2350 kgm–3. However.1: Building materials and their densities. (IAEA-47) Building material Density (kg. Air Conditioning The treatment room as well as the control room should be air conditioned. A 5% composition by weight of boron in polyethylene is commonly used in neutron shielding doors in treatment rooms. After a number of collisions they become slow neutrons. The capture gamma ray spectrum in concrete extends to greater than 8. For therapy installations operating above 10 MV. The capture of slow neutrons by hydrogen in concrete results in a pronounced peak in the photon spectrum at 2. but some special dense building bricks are available. which have a density of around 3000 kgm–3.21 MeV. which has high hydrogen content to form an efficient neutron shield. Concrete contains a relatively high hydrogen content and is therefore efficient at shielding against fast neutrons. shielding against neutrons must be considered.473 MeV. Planning of Radiological Facility of cement in the mix. Steel plate is often used in existing rooms that need to be upgraded. which undergo capture reactions with many materials and penetrating capture gamma rays are emitted. while increasing the proportion of aggregate increases density. Preformed concrete blocks only have a density of 2000 kgm–3. The fast neutrons are reduced in energy by elastic scattering interactions with hydrogen. The steel plate is usually formed in 10 mm thick sheets and fixed one layer at a time to the existing wall. If using dense bricks.12). The lower end of the openings should be located at a minimum height of 2. Examples of such bricks are barites. Increasing the amount of water in the mix will reduce the overall density as air pockets may be left as the mix dries out. Slow neutron capture in the boron results in the production of a low energy gamma ray of 0. so any shield designed as a primary barrier against X-rays will be more than adequate against photo neutrons. it is important to use heavy mortars to avoid shine paths between the bricks. Boron and cadmium have large cross-sections for the capture of slow neutrons. or barium and magnetite bricks.0 MeV and the average energy is 3. Ordinary sand mortar only has a density of 2000 kgm–3. taking care that the fixings do not overlie each other. The opening for the air conditioners should be provided in the specified outer wall of the treatment room in the case of Cobalt teletherapy room. Boron is incorporated into polyethylene. Each barrier should be formed in one pour to avoid seams between different layers. then special high density concretes or high density materials such as steel or lead can be used. The width of the baffle and the length of its vertical portion should be such that 30 cm wide overlap is available all around the 85 .5 m from the floor level outside and further be covered with a baffle arrangements (4. To guard against air pockets it is customary to vibrate the concrete mix as it is poured. If space is at a premium. The tenth value layer (TVL) for the primary X-ray beam is approximately double that for the photo-neutrons produced by medical linear accelerators.6 MeV. 4. It should be possible to see a Fig. For a two stage sign.13) must also be posted outside the room entrance or door. These signs should be mounted at eye level (1650 mm above finished floor level) and interlocked with the treatment unit control.12: Baffle design for air warning sign from any position within conditioner or exhaust the treatment bunker. the baffle arrangements are not necessary. A warning sign should indicate the nature of the hazard. the first stage will be illuminated when there is power to the treatment unit. If there are controlled areas with restricted access outside the treatment bunker these should be labeled appropriately. 86 Fig. to prevent entry of persons not connected with the examination or treatment. A suitable warning sign such as the redlight must be provided at a conspicuous place outside the room and kept ON when the unit is in use. The illuminated signs may have two or three stages. 4. 4. stage one will be illuminated when there is power to the treatment unit. If split type air conditioners are planned. Textbook of Radiological Safety openings. stage two will light when the treatment unit is programmed to deliver a radiation beam and stage three will illuminate when the beam is turned on. For a three stage sign. However conduit for passing the AC duct is to be provided in the specified wall at an angle to avoid direct scattered radiation passing through it.13: Radiation warning placard . and the second stage will illuminate when the beam is turned on. Warning Signs and Lights It is recommended that an illuminated warning sign be displayed at the entrance to the maze or treatment bunker. An appropriate warning placard (Fig. Planning of Radiological Facility Associated Facility The supporting facility of the radiotherapy department such as simulator room.15 B. treatment planning system. Similary. including the regulatory concern. and record room etc. examination room. 3. these plans are only models for teaching and training purposes. nurses room.17 respectively. 4. mould room. 87 . 2. 4. should be incorporated in the layout as shown in the Fig. by taking into account all the parameters. However. earth leakage circuit) must be ensured. 4. 4. Two way patient monitoring intercom system with two video cameras mounted in the treatment room and monitors in the control area in addition an independent intercommunication between treatment room and control desk. the model plan of a 6 MV and 15 MV linear accelerator is given in Fig.g.16 and 4. Medical physicists room.14 A typical lay out of a Tele-Cobalt installation is given Fig. Fire protection should be provided.14: A model layout of radiotherapy department Additional Installation Requirements 1.15 A and the cross sectional view is given in 4. The intercom should be voice activated or permanent one. Electrical protection as per the local regulation (e. one has to individually design the facility for the local need. Heat detectors or photoelectric smoke detectors are recommended. radiation oncologists room. Fig. Do not locate in the primary beam. CCTV to monitor the patient and treatment.15 A and B: A model tele therapy cobalt installation 4. one fixed and one movable 88 camera. 4. . Textbook of Radiological Safety Model Plan 1 (A) (B) AA cross section Fig. concrete density 2. CC:CC Cross sections.16: Model layout of a 6 MV high energy linear accelerator 89 .4-2.06 = 113. 4. Fig. Planning of Radiological Facility Model Plan 2 BB: cross section Not to scale. all dimensions are in meters. L: Lasers. Sagittal laser height: 2. BB: BB Cross section.295 m from finished floor.28 × 10. isocenter height =1.6 m AA: AA Cross section.47 sq m.35 g/cc Area : 11. 4-2. BB: cross section 90 Fig.77 sq m. Textbook of Radiological Safety Model Plan 3 Not to scale.6 m AA: AA Cross section. 4. all dimensions are in meters and concrete density 2.97 = 138.295 m from finished floor. sagittal laser height: 2. BB: BB Cross section.65 × 10.35 g/cc.17: Model layout of a 15 MV high energy linear accelerator . Area : 12. isocenter height=1. L: Lasers.CC:CC Cross sections. Planning of Radiological Facility 5. CCTV monitors may be mounted on or under shelf and must be visible during treatment. 6. Provision of In room monitor to have free view from every side of the couch. Do not locate in the primary beam. 7. Lasers should be fixed at a height of 2.4-2.6 m from finished floor level. Do not locate in the primary beam. 8. Provide battery working emergency light. 9. Provide an outside phone line for remote diagnostics modem. 10. Environmental specifications: Humidity range:40% to 80 % relative humidity, non condensing, Temperature range: 19° to 27° C. 11. The room lights, setup lights, closed circuit television system and In room monitor can be controlled by a single room master switch, often outside the room. The room lights can be on a separate circuit. 12. Set up lights are usually located above and to either side of the longitudinal axis. The operation is independent of the pendant and couch controls. 13. Provide a dimmer switch for set up lights, to adjust the illumination level, so that they are dim enough for clear visibility of the lasers. 14. Provide emergency off switches in room, but do not locate in primary beam. 15. Provide a key switch located at the control console to switch ON/OFF the In room monitor and all monitors and printers at the control console. 16. Provide enough power outlets at the control console and also near the back of the accelerator and the modulator. 17. Provision for wedge tray and compensator tray storage. 18. Provision for block tray storage. 19. Provision for electron applicator storage. 20. Provision for immobilization (acquaplast) systems. BRACHYTHERAPY FACILITY DESIGN Brachytherapy is a radiation treatment with sealed radioactive sources that may be placed within body cavities, within the tissues or very close to the surface to be treated. The duration of the treatment may range from a few minutes for HDR brachytherapy up to several days for LDR interstitial therapy. Many different nuclides are available for clinical use. They may be of low energy requiring minimal shielding or high energy requiring the use of specially designed rooms. LDR brachytherapy is performed either by manually loading sources into applicators that have been positioned in the patient or by remote after loading. The remote after loader stores the sources in a shielded position and, when required, will drive them into the applicators. It will also retract the sources during the treatment, whenever a person needs to attend to the patient and also at the end of the prescribed treatment time. 91 Textbook of Radiological Safety Rooms used for LDR Brachytherapy may not need special shielding. The layout of the room should allow patients to be nursed safely and also to be used for nonbrachytherapy patients. HDR brachytherapy is only performed with remote after loading units,and requires special facilities. When designing a room for brachytherapy, the following points should be considered: i. Which treatment techniques will the room be used for? ii. What is the likely number of patients per day/week/year? iii. How much radioactivity will be used per treatment/procedure? iv. Which nuclides will be used and what is their energy? v. Where will sources be stored prior to use and after their removal? vi. How will the security performance objectives for brachytherapy be achieved? In brachytherapy, the protection must be sufficient to reduce the primary and scattered radiation to the design limit in all directions since the sources are unshielded in all directions. The dose rate within the room will be much more higher and the room will be designated as controlled area. The dose rate outside the brachytherapy room should be reduced to less than 1 mSv per year. The patient receiving brachytherapy will attenuate the radiation. The extent of the attenuation will depend on the energy of the nuclide in use, the size of the patient and the location of the source(s) within the patient. Since brachytherapy sources are not collimated, the shielding requirements will be based on the transmission of the primary beam through the barriers. If possible the room should be designed so that there is no direct line from the door to the patient’s bed. If there is sufficient space for a maze, a protected room door may be unnecessary, but otherwise a lead- lined door will normally be needed. A β,γ monitor which measures the dose rate in the patient area should be clearly visible at the entrance to the controlled area. It is recommended that there be remote viewing of the patient from the nurse’s station by closed circuit TV, together with a two way intercom to reduce the amount of time nursing staff need to spend in the radiation environment. It should be possible to view access to the room from the nurse’s station. LDR and MDR Treatment Rooms For remote after loading systems (either LDR or MDR) the treatment room door will be interlocked to the after loading unit so that the radiation exposure of nursing staff is minimized. Mobile lead shields may be used to reduce radiation dose rates when ideal requirements are not possible. The weight and the need to maintain manoeuvrability of the shield limit the thickness and size of mobile lead shields. Lead shields typically have a thickness of 25 mm and a shielded area of 700 to 1000 mm by 500 to 600 mm. They are usually designed to protect the abdomen of a worker who 92 stands behind them. Planning of Radiological Facility Some after loading machines allow the treatment of more than one patient at a time so a suite of rooms will be required. Space will be needed for the after loading machine itself and the source transfer tubes. Ideally, the after loading unit will be stored outside the treatment room in a separate closed area. This allows for servicing of the unit when a patient not receiving Brachytherapy occupies the treatment room. HDR Treatment Rooms HDR remote after loading units need special facilities. All the walls, the floor and the ceiling will be primary barriers and must be of adequate thickness to protect the staff, who remain outside the room during the patient treatment. It is advisable to limit the position of the source within the room otherwise all the shielding requirements will need to be determined based on the source being in any position within the room. This may make the barriers unnecessarily thick. HDR sources are usually 192 Ir or 60Co. For both sources, the high activity and HDR require that the room have concrete barriers 400 to 800 mm thick. They will also need a heavy lead door unless a maze has been included in the design. HDR units are often installed in former radiotherapy treatment rooms that already have sufficiently thick walls, ceilings, floors and mazes or shielded doors. In HDR brachytherapy, the patients are often treated directly after the appliances have been positioned. Ideally, there will also be an X-ray facility within the room so that the correct placement of the applicators can be confirmed immediately prior to the treatment being delivered. A waiting Fig. 4.18: Model plan for a HDR brachytherapy room 93 Textbook of Radiological Safety area for a patient on a trolley may be required where the patient may be nursed while the treatment planning calculations are completed. A HDR facility should have an interlocked room door so that the source is returned to the safe position whenever the door is opened, and there should be a radiation warning sign at the room entrance indicating the ‘on-off’ status of the source. A model layout of a HDR room is shown in Fig. 4.18. Area: 9.5 × 6.6 = 62.7 Sq.m. Wall: Concrete 45 cm, density 2.35 g/cc Z.M: Zone monitor at 2 m from floor D: Door ordinary with a glass to peep window. BIBLIOGRAPHY 1. AERB safety code: Brachytherapy sources equipment and installations, AERB / SC / MED-3. 2. AERB safety code: Medical diagnostic X-ray equipment and installations, SC / MED-2 (Rev.1). 3. AERB safety code: Nuclear medicine facilities, SC/MED-4(Rev.1). 4. AERB safety code: Telegamma therapy equipment and installations, SC/ MED-1. 5. Basic radiological physics, Thayalan K. Jaypee brothers Medical publishers (P) Ltd. New Delhi 2001. 6. IAEA safety report series 47: Radiation protection in the design of Radiotherapy facilities, 2006. 7. Nuclear medicine resources book, IAEA, Vienna, 2006. 8. Planning of Teletherapy installations, Users guide, BARC/ RPSD /RASS / TELE-3, 1995. 94 Chapter 5 Radiation Monitoring Radiation exposure must be monitored for both personnel safety and regulatory purposes and it should be carried out periodically. It should also ensure the safety of personnel, patients and the public. The Atomic energy (Radiation protection) rules, 2004 (Earlier RPR-1971, Atomic Energy Act, 1962) insists the radiation monitoring a mandatory one. As per the rules all radiation workers should be monitored with a suitable radiation detecting device. There are two type of monitoring namely (i) Personnel Monitoring and (ii) Area monitoring. PERSONNEL MONITORING The aim of personnel monitoring is stated as follows: (i) Monitor and control individual doses regularly in order to ensure compliance with the stipulated dose limits, (ii) Report and investigate over exposures and recommend necessary remedial measures urgently, (iii) Maintain life time cumulative dose records of the users of the service. Hence, the radiation received by all the radiation workers during their work should be regularly monitored and a complete up to date record of these doses should be maintained. Personnel monitoring is usually done by employing (i) Film badges or (ii) Thermoluminescent dosimeters (TLD) or optically stimulated luminance dosimeter (OSL), and (iii) Pocket dosimeter. The personnel monitoring devices provide (i) occupational absorbed dose information, (ii) assurance that dose limits are not exceeded, and (iii) trends in exposure to serve as check on working practice. In India, country wide personnel monitoring service is offered by the Personnel dosimetry and dose record section, Radiological Physics & Advisory Division (RPAD), CT&CRS building, Bhabha Atomic Research Centre (BARC), Anusaktinagar, MUMBAI-400094.The BARC has accredited M/s Avanttech laboratories (P) Ltd, Chennai and M/s Renantech Laboratories (P) Ltd, Mumbai, to provide personnel monitoring services in India. The requirements of an ideal personnel monitoring systems are (i) instantaneous response, (ii) distinguish between different types of radiation, (iii) accurately measure the dose equivalent from all forms of ionizing radiation with energies from keV-MeV, (iv) independent of angle incidence, (v) small, light weight, rugged, easy to use, (vi) inexpensive, unaffected by environment conditions (heat, humidity, pressure), and (vii) unaffected by Textbook of Radiological Safety non ionizing radiation. No such dosimeter, satisfying all the above features is available as on date. However, one can be satisfied to some extend by selecting a particular type for a given application. FILM BADGE A film badge is used to measure external individual doses from X, beta, gamma and thermal neutron radiations. It consists of a film pack loaded in a film holder having suitable metallic filters. The film holder is made up of plastic with stainless steel lining as shown in the Fig. 5.1. It is capable of holding one or more photographic films of size 4 cm × 3 cm, wrapped inside by a light tight polythene or paper cover. The metallic filters are fixed on both sides of the holder which help to identify the type and energy of incident radiation. There are three types of holders (i) chest holder, (ii) wrist holder, and (iii) head holder. The film should be loaded in the film holders, so that the flap side of the film pack is always facing the body. Fig. 5.1: Film badge The film holder has 6 filters namely open, plastic, cadmium, thin copper, thick copper, and lead. All the filters has 1mm thick except thin copper which is 0.15 mm thick. The filters assess the penetrating power of the radiation and thus permit the energy to be estimated. Thus, it will identify alpha, beta, neutron, low energy X-rays, high energy X-rays and gamma rays, over a range of energies from 10 keV to 2 MeV. There are two films in the badge, one is slow and the other is fast. The slow film is meant for 96 recording high exposure. Film badge is worn compulsorily at chest level. If the film badge is worn under the apron at chest level. TLD card: The TLD card consists of 3 CaSO4: Dy-teflon disc of 0. Using standard calibration curves.8 mm thick and 13. and (iii) least expensive device. It gives very reliable results since no fading is observed under extreme climatic conditions. the emission of light when certain materials are heated after radiation exposure. the dose under each filter is evaluated.2 mm diameter each. The card is enclosed by a paper wrapper in which users personnel data and period of use is written. loaded in a chest holder as control. The supply of film is for a period of one calendar month (4 weeks). The film badges are used only by persons directly working with radiation sources. It does not protect the user from the radiation. pressure and chemicals. Film badge can be used to measure radiation from 10 mR to 1000 R with a accuracy of ± 10%. Hence. which are mechanically clipped over three symmetrical circular holes each of diameter 12 mm. The thickness of the wrapper (12 mg/cm2) makes the measurements equivalent to 10 mm depth below the skin surface. complex dark room procedure and limited self-life etc. the optical densities under different filters are measured by a densitometer. Radiation Monitoring a lead apron is used. Each institution should keep one film. on a nickel plated aluminum plate (52. The advantages of film badge are (i) it is a permanent record (ii) nature of exposure. 1. 5. It is also worth to note that the film badge is used to measure the radiation dose to which the user is exposed. types of radiation and energy can be evaluated. beta and gamma radiations. An asymmetric V cut provided at one end of the card ensures a fixed orientation of card in the TLD cassette. where the film is processed. THERMOLUMINESCENT DOSIMETER The film badge has some disadvantages such as fading at high temperatures and humidity. After 4 weeks the film is returned to the agency for dose computation. It is used to measure individual doses from X.9 mm × 1 mm). 97 . high sensitivity to light. The doses are reported in mSv and the minimum dose that a film badge can detect is about 0. It is based on the phenomenon of thermoluminescence. thermoluminescent dosimeter (TLD) badges are used currently in India instead of film badges. These reports contain monthly doses and up to date cumulative doses of the current year.2. The typical TLD badge consists of a plastic cassette in which a nickel coated aluminum (Al) card is placed as shown in the Fig. To protect the TLD discs from mishandling. Monthly dose reports are sent to the individual institutions after processing the film packs.2 mSv. When radiation passes through the filter it causes formation of the latent image in the film. This control badge should be kept in a cool. A control film is always needed to assess the background level of radiation. The film badge worn at the chest level represents the whole body dose equivalent.5 mm × 29. dry and radiation free area. 2: TLD badge Al cards and its holder with filters The metallic filter is meant for gamma radiation. The PMT signal is then amplified and measured by a recorder. The pouch also protects the card from radioactive contamination while working with open sources. Textbook of Radiological Safety the card along with its wrapper is sealed in a thin plastic (polythene) pouch. 5. the electron return to their ground state with emission of light. There are three filters in the cassette corresponding to each disc namely. The reader is calibrated in terms of mR or mSv. After radiation exposure the dose measurements are made by using a TLD reader (Fig. The third disc (D3) is positioned under a circular open window.9 mm Cu (thick:1000 mg/cm2). This badge 98 can cover a wide range of dose from 10 mR to 10. 2. so that one can get direct dose estimation. The filters are mainly used to make the TLD discs energy independent. which converts light into an electrical current (signal).5 mm thick plastic filters (180 mg/ cm2). The reader has heater. While heating. When the TLD card is inserted properly in the cassette.3). There they form a trap just below the conduction band. A clip attachment affixes the badge to the users clothing or to the wrist. The discs are reusable after proper annealing. and the perspex is for beta radiation. and a recorder. where it is heated for a reproducible heating cycle. TLD cassette: TLD cassette is made of high impact plastic. This emitted light is measured by the PMT. The number of electrons in the trap is proportional to the radiation exposure and thus it stores the absorbed radiation energy in the crystal lattice.000 R with a accuracy of ± 10%. the electrons in the crystal lattice are excited and move from the valency band to conduction band. The copper filter is nearer to the TLD disc and the Al should face the radiation. Perspex and open. The TLD disc is placed in the heater cup or planchet. Cu + Al. Fig. . 5. When the TLD disc is exposed to radiation. amplifier. The second disc (D2) is sandwiched between a pair of 1. Photo multiplier tube (PMT). the first disc (D1) is sandwiched between a pair of filter combination of 1 mm Al and 0. TLD badge is used to measure the radiation dose. that is expected to receive the maximum radiation exposure. TLD badges are to be used only by persons directly working in radiation. Additional wrist badge is advised for procedures involving nuclear medicine. 10 mSv to 1000 Sv. should be written legibly in block letters on the front side of the badge. which has wide dose response. The name. personnel number. Administrators. They can handle one or more planchets at a time either with manual drawer or computer controlled drawer function. Fig. During fluoroscopy.3: TLD reader for dose estimation Guidelines for Using TLD Badge 1. discs. need not be provided with TLD badges. period of use. ribbons. 5. Its effective atomic number is close to that of tissue with an accuracy of ± 2% TLD badges are normally worn at the chest level.. location on the body (chest or wrist) etc. TLD badges do not provide a permanent record and it is available for extremity dosimetry and finger dosimetry (ring). They are capable of analyzing TLD chips. pellets. It does not protect the user from the radiation. 3. Programmable annealing oven is also available along with the system. 99 . it is preferable for the radiologist to wear at the collar level in front of the lead apron to measure the dose to the thyroid and lens of the eye.. 2. sweepers etc. LiF can also be used as TLD phosphor. powder. dark room assistant. type of radiation (X or gamma). Most of the radiation workers used to wear the badge at the waist level which is not correct. They display digital glow curve and temperature profile. since most of the body is shielded from the radiation exposure. brachytherapy source handling and interventional radiology. Pregnant radiation workers should wear a second badge at waist level (under the lead apron) to assess the fetal dose. Radiation Monitoring Now a days widows based computer controlled TLD readers are available. rods and microcubes. In addition to the regular film badges. . Each institution must keep one TLD card loaded in a chest TLD holder as control. 10. TLD badge should be worn compulsorily at the chest level. laser is used to stimulate light emission. It represents the whole body dose equivalent. Every new radiation worker has to fill up the personnel data form. Optically Stimulated Luminance Dosimeter Dosimeters using optically stimulated luminance (OSL) is also available now a days alternative to TLD. Bhabha Atomic Research Centre. Personnel dosimetry & Dose record section. This is very useful in nonroutine work. Anusakti nagar. ovens. 9. which gives instantaneous radiation exposure. Instead of heating. Textbook of Radiological Safety 4. and should be sent to BARC. Crystalline aluminum oxide activated with carbon (Al2O3: C) is commonly used as OSL dosimeter. where there is no likely hood of any radiation exposure. CT & CRS Building. 11. 5. which is required for correct dose evaluation. If lead apron is used. POCKET DOSIMETER Film and TLD will not show accumulated exposure immediately. Mumbai or to the accredited agency. It is replaced by a new holder. Radiological physics & Advisory division. Every radiation worker must ensure that the badge is not left in the radiation field or near hot plates. after every service period (quarterly) in one lot so as to reach 10th of next month/quarter. While leaving the premises of the institute. It has broad base response and capable of detecting low doses as 10 mSv. The principle of OSL is similar to TLD except the heating. All the used or unused TLD badges should be return. 7. in which the radiation levels vary considerably and may be quite hazardous (cardiac cath lab). The dose can be read off directly by the person during or after any radiation work. burners etc. Contact for all correspondence regarding TLD badge service. The main advantage of pocket dosimeter lies in its ability to provide instant on the spot check of radiation dose received by the personnel. It should be stored in a radiation free area. the radiation doses received by the radiation worker can be assessed by wearing a pocket dosimeter. 8. furnaces. A TLD badge once issued to a person should not be used by any other person. 6. Suitable protective measures can be undertaken 100 immediately to minimize future exposures. Mumbai-400094. 12. to the officer in charge. TLD badge should be worn under the lead apron. A badge with out filter or damaged filter should not be used. The OSL dosimeter can be re read several times and it can also differentiate between static and dynamic exposures. workers should deposit their badges in the place where control TLD is kept. The Roentgen is the unit of exposure = 2. smallest range (0-200 mR) should be employed. on a wire frame as shown in the Fig. It has a built-in capacitance which can be charged by an external potential (charger). reducing the coulombic repulsion and allowing the fiber to move. ion pairs are produced in the air. These ion pairs partially neutralize the positive charge.876 rad) of air dose. Radiation Monitoring It is an ion chamber with a quartz fiber suspended with in an air filled chamber.4: Pocket dosimeter These dosimeters should be fully charged prior to their use so that the initial reading of the dosimeter is set at zero. The quartz fiber is bent away from the frame due to coulombic repulsion. It can detect photon energies from 20 keV-2 MeV.5. which is measured in Roentgen (R). These dosimeters 101 .76 mGy (0. 5. the quartz fiber move closer to the wire frame. 0-5R. When exposed to radiation.0-200R and 0-600R for measurement of X and gamma rays. The dose in air can be calculated from the exposure. This can be visible through an optical lens system upon which an exposure scale is superimposed. Fig.4. by means of the charger. The dosimeter is available in different ranges varying from 0-200 mR. that can be seen as down range excursion of the hair line fiber on the exposure scale (graticule). The movement of the quartz fiber is proportional to the radiation exposure. The positive charge is placed on the wire frame. 0- 500 mR. Hence. where 1R exposure is equal to 8. 5. 0-20R. 5.58 × 10-4 C/kg. For personnel monitoring. A typical commercial chamber with charger is shown in the Fig. Sudden mechanical shock may result in wrong reading. The energy range of these dosimeters are 45 keV to 6 MeV and are available in mR and mSv display. The sound become more frequent as dose rate increases. Textbook of Radiological Safety are available both in analog and digital types. Fig. The dose measurement range of pocket dosimeter is 10 μSv to 100 μSv. 5. matching to TLD badges. (iv) not wearing the dosimeter while working in radiation. Most of the time the workers . Now a days digital pocket dosimeters are available with easy display of instant radiation measurements. and becomes continuous sound at high radiation fields. the attenuation 102 will cause a significant reduction in exposure. The accuracy of the pocket dosimeter is about ±10%. They make loud beep sounds for every 15 to 30 minutes on background. Digital dosimeters use either GM tubes or diodes and solid state electronics.5: A commercial pocket dosimeter with charger PERSONNEL MONITORING SYSTEMS AND FEATURES The common problems associated with personnel monitoring dosimeters includes (i) leaving dosimeters in a radiation field. these dosimeters should be handled with care so as to indicate reliable reading of the doses received. Presently semiconductor diode based pocket dosimeters with digital display are also available. (ii) radionuclide contamination of the dosimeter. If the body is between the dosimeter and radiation source. (iii) lost or damaged dosimeters. Pocket dosimeters are small in size and easy to use and do not provide permanent record. Hence. when not worn. with reliable readings. They have good energy and polar response. the dose limit in any single year should not exceed 30 mSv. γ. BARC. RPAD. As a result the radiation exposure becomes multidirectional and the recorded value is the average exposure for that individual.e.000/mSv TLD β. The Radiological Physics and Advisory Division (RPAD). The radiological safety officer (RSO) of the concerned institution should examine the working conditions and the circumstances that might have resulted in to the above excessive exposure and report the details to Personnel dosimetry and Dose records section. Radiation Monitoring do not remain in fixed geometry. i. X-rays 0-200 mR Special monitoring 0-500 mR Direct reading 0-5000 mR AREA MONITORING The assessment of radiation levels at different locations in the vicinity of radiation installation is known as area monitoring or radiation survey. Permanent record β: 0. 2. average 20 mSv for every year of the sliding 5 years block. On the basis of measurements taken.000 mSvb. The various type of monitoring systems are summarized in Table 5.1. from the date of receipt. A written statement from the individual.1-15. one could confirm the adequacy or 103 . X-rays 0. It is with in ± 10-20% of the individual’s true exposure. X-rays 0. in the given proforma within 15 days. γ. X-rays γ: 0. while doing radiation work.1: Comparison of personnel monitoring systems Dosimeter Radiation Range Features Film badge β. the effective dose constraint for consecutive 5 years shall be 100 mSv. BARC will advise the respective institution to take the following actions: 1. These measurements will give an idea about the radiation status of the installation. explaining the causes for the reported exposure should also be forwarded along with the RSO investigation report. γ. it will be considered as over exposure and the same is reported promptly to the institution and the individual. As per the existing AERB regulatory limits. This is to take preventive steps to avoid such exposure in future.01-106/mSv No permanent record Patient dosimetry OSL β.5-10.01-106/mSv Reread dosimeter Differentiate static and dynamic exposures Pocket dosimeter γ. Overexposure If a person receives more than 10 mSv in one quarter. Table 5. before they recombine. zone monitors and door way mounted meters etc. They are available in the form of vehicle mounted radiation meters. Textbook of Radiological Safety inadequacy of the existing radiation protection status. Since ionization chambers collect only primary ions. The movement of ions produces an electric current in the outer electronic circuit of the chamber. and 3. any survey meter/ area monitor should consists of two main parts namely: 1. Scintillation detector type [NaI (Tl). positive and negative ions are collected respectively by cathode and anode of the chamber. response of detector for the energy and type of radiation etc. energy discrimination is possible with ionization chambers for heavily charged particles by pulse height analysis. Ionization Chamber Survey Meter Ionization chamber usually consists of an outer cylinder (cathode) coated inside with graphite to make it conducting and a central electrode (anode) insulated from the chamber wall (Fig. Selection of a particular detector depends on a variety of factors like type of radiation to be detected and quantity to be measured. the radiation produces ionization in the gas. Following are the different type of meters generally used for radiation survey and area monitoring: 1.6). Geigher-Muller (GM) type (Neon and halogen). They can be used as portable radiation survey meters. A device which detect the radiation. Under suitable electric field. The cylinder is filled either with air or suitable gas acting as an interacting and detection medium and a suitable voltage is applied across the electrodes. and 2. During this mode. 5. suitable remedial measures can be taken. electronic amplification of charge is necessary for display purpose. In general. Hence. A display system to measure the radiation. ZnS (Ag)]. Instruments used for the above purposes are called radiation survey meters and area monitors. any change in the applied voltage will not affect the number of ionizations produced in the chamber by the radiation. Ionization type (air) 2. Number of ionizations will be purely dependent on the energy dissipated in the medium. This makes ionization chamber based 104 instruments somewhat delicate and susceptible to extreme climatic . These instruments differ from each other in the medium in which the response takes place and in the method by which the response is detected and quantified. In ionization chambers the electric field applied is only just sufficient to collect all the primary ions produced by radiation. The strength of this current is proportional to the number of ionization events caused by the energy absorbed in the air chamber and will serve as a measure for quantifying the exposure/exposure rate or dose/dose rate. capable of measuring radiation count rate in mR/h or μR/h. In case the radiation levels are found to be higher than the permissible levels. When the chamber is exposed to radiation. Radiation Monitoring conditions. 0-50 mR/h. pressure. It is capable of measuring gamma energy >25 keV. 0-5 R/h. These current is very small (pico-nano Ampere) and requires very sensitive electrometers for measurement. It is recommended to use pressurized ion chambers (8 atmospheres or 125 psi) for in radiotherapy. and available in different ranges: 0-5 mR/hr. Fig. 0-500 mR/ h. and 0-50 R/hr. 105 . They response slowly (8-2 seconds) to rapidly changing exposure rates and hence needs warm up and stabilization before measurements are made. A typical survey meter consists of a 500 cc chamber connected to a battery operated electrometer and can measure exposure rates from a few mR/h to about 10 R/h. these are operated in current modes. These limitations are less important in medical applications (5% loss of exposure rate at 10 R/hr). They approximate the condition under which the roentgen is defined. photon energy and exposure rate. 5. tufnol) and they can be used over a wide range of energies from 7 keV to 2 MeV. Ionization chambers for low level X-ray monitoring (exposure/ exposure rate) are fabricated out of air-equivalent materials (bakelite. and in monitoring radionuclide therapy patients. They allow fast response time to radiation leakage.6: Ion chamber Ion chambers for radiotherapy are fabricated with phenolic wall material with 200-350 cc chamber volume and operated both in dose and dose rate mode. Ion chambers are used to measure X-ray machine outputs. Ion chambers are influenced by changes in temperature. Ionization chambers are used whenever accurate measurements are required. estimate radiation levels in brachytherapy. and survey the radioactive material packages. Some of these are provided with an end window of thin mylar film for beta radiation detection. and beta energy >1 MeV. scatter beams and pinholes. Ion chambers are capable of monitoring higher radiation exposure rate levels. They provide enhanced sensitivity and improved energy response for the measurement of dose and dose rate. For X-ray and gamma ray dose measurements. In addition. the low noise chamber bias supply provides for fast background settling time. neon and chlorine/ bromine). type and energy of radiation). Since. use of very thin wire as the anode enables the production of high electric field close to the anode.7).5-2 mg/cm2).g argon and neon). which is filled with a gas of low electron attachment coefficient (e. and Gamma rays (> 6 keV) radiations. It is suitable to measure natural background radiations. communications interface with windows based excel add-in for data logging. 5. since it dose not reproduce the conditions under which exposure is defined. Since electronic amplification is not necessary. but relatively insensitive to and 106 gamma radiations. optional beta slide. beta (> 45 keV) X. This feature makes the GM type instruments rugged and less costly. compared to that of ionization chamber. The primary photons interact with the cathode materials to produce secondary electrons. . simultaneous measurement of dose and dose rate. The gas amplification ( ≈ 108) is independent of primary ionization (i. It provides measurements in counts per minute (cpm). GM type instruments are very sensitive and useful for monitoring of low level radiation. the electronic circuit of GM is very simple. This results in an amplification of ionization events in the chamber. This is known as gas amplification (avalanche) which depends on the nature of gas and the pressure of gas. Also the primary avalanche is followed by a successive avalanches due to secondary phenomena (excitation of gas atoms and production of UV photons). GM detector is sensitive to particle radiation. they should be used only in X-ray units. that emits continuous X-rays. It will respond to alpha (> 3 MeV). The electrons produced in the chamber will have sufficient energy to produce secondary and tertiary ionization during their acceleration towards anode. the whole wire is covered by a sheath of electrons.e. It detect the presence and provide a semi quantitative estimate of the radiation field magnitude.g. In GM counters. that emits pulsed X-rays (e. GM counters for X-rays and gamma rays monitoring use copper or chromium cathodes for better efficiency (Fig. and large surface area. Hence. GM type meters mainly used as radioactive contamination monitor with thin window (1. GM counters used for radiation monitoring generally use a mixture of gases (argon. But the relationship between cpm and mR/hr is a complicated function of photon energy. It also provides an approximate measurement of mR/hr. programable flashing LCD display and audible alarm with dose equivalent energy response (SI units). operated by two 9 volts alkaline batteries check source. GM meters are pulsed in nature. Textbook of Radiological Safety Now a days survey meters are provided with lot of special features like auto ranging and auto zeroing. GM Type Survey Meters In GM survey meter a higher electric field (500-1300 V) is applied between anode and cathode of a chamber. Linear accelerators). They should not be used in X-ray units. Radiation Survey Radiation survey is a procedure in which the exposure rates are measured in and around a radiological equipment by using suitable survey instruments. until the radiation survey is carried out. nuclear medicine require weekly radiation survey. collimator. Radiation survey protocol should be made by the hospital for a specific equipment.7: GM type radiation survey meter RADIATION SURVEY IN DIAGNOSTIC RADIOLOGY Introduction The aim of conducting radiological protection survey of a diagnostic installation is to ensure that good quality images are obtained with minimum doses to patients. The various procedures involved in the radiation survey. for each discipline are explained in the following pages.000 cpm measurements. The surveillance program also fulfill the requirement in respect of filter. They should not be used in high level radiation fields or when accurate exposure rates are required. leakage radiation. safe work 107 . It also ensure that the radiation doses received by the radiation workers are as low as reasonably achievable (ALARA) and they are unlikely to receive doses higher than the maximum permissible limits. This is to safety status the quality of the radiological unit. It is to be carried out at time of installation. No machine should be subjected for patient use (either imaging or treatment). GM counters have long dead time (100 μsec) and result in 20% loss at 100. It is mainly used in nuclear medicine for low level contamination surveys. 5. Fig. repeated weekly/quarterly/ annually or after every major repair of the radiation equipment. quarterly survey for radiotherapy and annual survey for diagnostic radiology. Radiation Monitoring which are 50-100 cpm. For example. opening in the walls etc. Ensure that warning sign (red light and placard) is provided at the entrance of diagnostic room to restrict the entry of public during the 108 operation of diagnostic equipment. Radiation protection survey is the evaluation of potential radiation exposure levels at various locations in the installation and the leakage levels incidental to the use of diagnostic equipment under specified conditions.. The focus-to-table top distance should not be less than 30 cm for fluoroscopy units. 3. 5. Textbook of Radiological Safety practices and proper installation planning. Ensure that control panel is sufficiently shielded with lead lined protective barrier having lead glass windows giving clear view of the rest of the room. The evaluation includes: (i) inspection of the equipment. mammography. General Checks 1. other occupied areas in the immediate vicinity of X-ray room. dark room. Separate protocols of radiation survey should be made available for general X-ray unit. . 7. Total filtration 3. fluoroscopy and CT scanner. Inspection of the Equipment 1. Ensure that protective devices like lead apron. patient’s waiting area. lead rubber gloves etc.0 meter for all normal radiography and up to 2. (ii) examination of its location with reference to controlled and noncontrolled areas in the immediate environment and (iii) measurement of exposure levels in the environment arising from the operations of the equipment. Ensure that the X-ray diagnostic equipment is so installed that under no circumstances the X-ray beam is directed towards entrance door.to. 2. 4. Ensure that the walls for exhaust/ventilation are provided at least 2 meters above the finished floor level outside and otherwise that the openings are provided with sufficient shielding. Check whether the timer of fluoroscopy machine is functioning properly. There should be provision for audible signal at the end of the preset time. Check the dark room layout and ensure that the safe light and processing unit are adequate. 6. The maximum range of timer should not exceed 5 minutes. Table top exposure. Check whether the focus.table distance is as per the specification. are provided and are in good condition. Tube screen alignment 4.0 meter for chest radiography. film storage. 8. The X-ray unit should permit a focus–film distance of at least 1. Tube housing leakage 2. But there are some general requirements of survey for all the above equipments. The machine is operated under maximum kVp and nominal mA settings. it is necessary to know the work load. The location of the control panel. to create maximum scatter conditions. 3. The source to image distance (SID) is kept as 100 cm. To calculate the work load. behind 4 walls of the room. A water phantom (30 × 30 × 30 cm3) to simulate patient scatter condition or a plastic bucket ( ≈ 9 liters) full of water. below the floor (if the unit is not in the basement) dark room any other location of interest. using a ion chamber type survey meter. dark room and patient waiting areas are indicated in the sketch. passages. Total mAs examination per day per week per week Chest 15 25 25×5 15 × 25 × 5 =1875 Skull 40 5 5×5 40 × 5 × 5 =1000 Extremities 10 20 20×5 10 × 20 × 5 =1000 Abdomen 100 10 10×5 100 × 10 × 5 =5000 Total workload.2. of exams. These locations include control panel. doors. radiologist position. n ∑N E j=1 j j W= =( ) mA min/wk 60 Table 5. Measuring tape. mobile protective barrier. mAs per week = 8875 Total workload.9 Survey Procedure The sketch of the layout of the installation is drawn and dimensions of the room is measured. No. A model workload calculation is given in Table 5. the number of exposures (Nj) of various types (j) per week is noted. The collimator is opened for its maximum field size. doors (both opened and closed position). This is repeated for both vertical and horizontal orientations of the X-ray room. mAmin per week = 8875 / 60 min = 147. A water phantom of not less than 30 × 30 × 30 cm3 dimension is set on the table. of exams. The radiation levels are measured at various locations. 109 . 2. The average mAs (Ej) for each such exposure should also be noted. Workload To establish the doses that are likely to be received by the radiation workers and public. patient waiting area. ceiling. windows/ ventilators.2: A typical calculation of workload Type of mAs per exam. Radiation Monitoring Instruments and Accessories 1. Ionization chamber type survey meter. No. cassette pass box. Then the workload can be calculated by using the relation given below. the exposure level at the control panel is within permissible limits. Table 5. Note: The Permissible dose limit to radiation worker is 20 mSv per year or 0. Calculate the radiation level for a total work load of 148 mAmin per week at entrance door level.0 mSv per year or 0. Calculate the weekly exposure received by the operator(assume work load as 148 mAmin/wk). Textbook of Radiological Safety With the knowledge of the workload. The weekly Radiation level = (180 mR/100 mA60 min) × 148 mAmin / week = 4. the radiation exposure per week. Hence. The weekly exposure =(360 mR/60 mA60 min) × 148 mAmin / week = 14. Note: The permissible dose limits for the general public is 1. Example 3: The exposure level at the corridor is 30 mR/h (for tube current 60 mA). .3: Radiation survey measurements Locations Exposure rate level (mR/hr) Beam facing up Beam facing down Horizontal beam Example 1: If the unit is operated for 100 mA and the exposure level measured at entrance door is 180 mR/h. calculate the weekly exposure to the public (assume the workload as 148 mAmin). The exposure level at the corridor =(30 mR/60 mA60 min) × 148 mAmin / week = 1. at various locations can be calculated by using the relation: Exposure rate measured ( mR/hr ) Radiation exposure = × W ( mA min/ wk ) 60 × mA =( ) mR/wk The measured readings are tabulated as shown below (Table 5.02 mSv per week or 2 mR/week. the exposure level in the 110 corridor is well within permissible limits. Example 2: The instrument reading is 360 mR/h (for tube current 60 mA) at the operator position behind the mobile protective barrier.44 mR/wk.3).23 mR/wk.4 mSv per week or 40 mR/week. Hence.8 mR/wk. Radionuclide Therapy I-131 is commonly used for the treatment of thyroid cancer and hyperthyroidism. sink. Once the patient is administered with I-131. GM counter survey is carried out at the above locations and are recorded in cpm. Later. Hence. Hence. but the later gives rise to significant radiation exposures. are indicated in the sketch.cm. followed by swipe test of the areas. fume hood. In addition. bedside. active toilet.cm for I- 131 respectively. at the end of the week. isolation ward and nurses station etc. ion chamber survey are also carried out in the above locations and recorded in mR/hr. The location of the machine room. Contamination is the major source of spread of radioactive material in nuclear medicine. shoes and clothing should be monitored for contamination by the contamination monitor. The accepted level of contamination limits are 0. exposure rates at 1 m from the patient. These instruments are kept at good working conditions and needs to be calibrated at regular intervals (once in 3 year). This will identify the areas of high exposure rates especially from radioactive waste and waste storage rooms. Swipe Test Swipe tests are performed by using small pieces of filter paper or cotton at various locations of the nuclear medicine laboratory. External contamination is not a series health hazard. Additional swipe tests are performed to confirm the decontamination. it is excreted in all the body fluids including urine. Personnel hands. doors and in the adjacent rooms should be measured with ion chamber type surveymeter. Hence. examination room. for Tc-99m and 0. contamination control methods are designed to prevent their spread to personnel and other work areas. Effective decontamination methods are employed to bring back the areas to normal level. The sketch of the layout of the Nuclear medicine laboratory is drawn and dimensions of the various rooms are marked. injection room. The 111 . control panel. Contamination is classified as (i) external contamination and (ii) internal contamination. Radiation Monitoring RADIATION SURVEY IN NUCLEAR MEDICINE Nuclear medicine radiation survey require the following instruments namely (i) Portable ion chamber survey meter and (ii) GM type contamination monitor. Areas that are having twice the background levels are said to be contaminated. patient waiting room. radioactive waste storage. internal contamination needs to be prevented by proper radiation survey. these swipes are counted under the NaI (Tl) gamma well counter.0001 μCi per 100 Sq. source storage.01 μci per 100 sq. The effectiveness of the contamination control is monitored by GM counter survey. saliva and perspiration. area survey. He has to investigate and advise corrective measures.2 GBq (33 mCi) at 1m from the patient. the room is decontaminated. The following radiation survey meters and items are made available for a 112 successful survey program. The survey will ensure that the exposure levels outside the room will not exceed the permissible limits. use factor and occupancy factor. until it comes down to 1. warning lights. Textbook of Radiological Safety measured levels are posted at the adjacent rooms with suitable instructions to the nursing staff and visitors. testing of interlocks. The area is isolated and posted with warning signal. calibration of the machine. The protective clothing of the personnel involved in the decontamination procedure should also be surveyed with GM counter. A minor spill is one in which the activity is less than a mCi. considering the dose rate. measurement of head leakage. The survey should duplicate the conditions that are expected during the patient treatment in terms of work load. (ii) Tele-Cobalt unit and (iii) Brachytherapy systems/sources. and emergency switches. If the spill involves volatile radionuclides. The exposure rate measurements are repeated daily. A good survey program includes checking the equipment specification. If it is more than a mCi then it is called major spill and the Radiation safety officer (RSO) should be informed. acceptance testing and commissioning. Hence. As a first step spills should be contained with absorbent material. machine on time. In the bioassay the personnel’s thyroid is subjected for external counting with a NaI (Tl) detector for radioiodine. specific radiation survey procedure is essential for each one. use factors. . then it may lead to internal contamination. followed by GM counter radiation survey for contamination purpose. Decontamination should be carried out from the perimeter of the spill toward the center to spread the contamination. while the hospital physicists take care of the acceptance testing and commissioning. Spillage Accidents may happen in nuclear medicine due to radioactive spill. This is followed by radioactivity measurement of urine. and occupancy factors for the adjacent areas. the medical physicists should carry out radiation protection survey of the installation. Radiotherapy uses three category of equipments namely (i) linear accelerator. After the patient is discharged. warranting bioassays. RADIATION SURVEY IN RADIOTHERAPY Setting up a Radiotherapy facility involves three major steps namely installation. The vendor does the installation part. After the installation. Decontamination is usually done by absorbing the spill and cleaning the areas with detergent and water. A swipe test and GM survey should follow to ensure decontamination. which may be minor or major spill. The machine is switched ON and the ion chamber reading is noted. Radiation Monitoring 1. The occupancy around the installations. controlled area and uncontrolled areas 113 . Fig. This will enable us to read the ion chamber through the TV monitor. 5. 5. the collimator is closed completely and it is covered with 2 TVL of lead shielding (Fig. The ion chamber is positioned at any one of the location point at 2 m from the source. Linear Accelerator Source ON Position Leakage The gantry of the linear accelerator unit is placed at 180°.2 % of the useful beam dose rate at the treatment distance. Consider 2 points on the poles of the sphere. Now. to cover the ion chamber location. The tolerance limit is 0. GM type Contamination monitor 3. for source ON condition Area Survey The sketch of the linear accelerator installation is drawn on a paper.8). 4 equally spaced points on its equator and distribute the remaining points uniformly on the surface of the sphere. The readings in exposure rates (mR/h) are noted for all the 20 locations individually. Pressurized Ion chamber survey meter 2. Choose 20 measurement points located on the surface of a sphere of radius 2 m from the source. The ion chamber position is changed to different location points around the head at the same 2 m distance from the source. Neutron survey meter (BF3) 4. Radiographic film 5. Water phantom.8: Linear accelerator. radiation survey leakage measurements in mR/h at 2m. The CCTV camera is positioned. . A wide range ion chamber may be used for the measurement..... Now the unit is switched ON and the exposure rate is measured in the above locations by using a wide range ion chamber survey meter.... Measure the exposure rate (mR/h) at 5 cm from the surface of the source head. . Head Leakage-source OFF Condition The gantry of the teletherapy unit is placed at 90 or 270 degree and the machine is switched off.... Similarly........ A water phantom (30 cm × 30 cm × 30 cm) is kept in the couch to create maximum scatter condition. at eight different positions around the gantry as shown in the Fig.... when the unit is loaded with maximum capacity source. Mark number of locations in the drawing.. the head leakage for both source OFF and source ON conditions and area survey of the installation are the essential procedures to be carried out...... 5..... the exposure rate measurements are repeated for different gantry positions of 90.. at a distance of 1m from the source. Head Leakage Source ON Position The gantry of the machine is positioned at 180 degree and the collimator is 114 closed completely and it is covered with 2 TVL of lead shielding (Fig.......... the exposure rates (mR/h) are measured at 1m distance from the source......... for different locations (8) around the source............... The tolerance limit is < 20 mR/h. above ceiling..... Similarly.180 and 270 degree. It is repeated to complete the measurements in all the locations. The gantry is kept at 0 degree position...... in which the exposure rate is to be measured... Textbook of Radiological Safety are marked in the drawing....... The linac machine is set at 100 cm (SSD).....10).. Gantry A B C D E F G H I position 0° 90° 180° 270° Cobalt-Teletherapy Machine Survey In the case of Cobalt-teletherapy machine radiation survey. door all four sides................9... with maximum field size (40 cm × 40 cm)... The tolerance limit is < 2 mR/h on the average and 10 mR/h maximum in any direction.. Model: ...... These locations may includes control panel. 5......................4: Measured exposure rates in mR/h at different locations Survey meter: Wide range ion chamber Make: . The readings are tabulated as shown below (Table 5..4): Table 5..... below floor and patient weighting area etc.... Date: ......... controlled area and uncontrolled areas are marked in the drawing. Fig. with maximum field size. These locations may includes control panel. for source measured in mR/h for source ON OFF condition position The ion chamber is positioned at 1m from the source around the head. in which the exposure rate is to be measured. The teletherapy machine is set at 80 cm (SSD). The tolerance limit is < 0. 180 and 270 degree. A water phantom (30 cm × 30 cm × 30 cm) is kept in the couch to create maximum scatter condition. This will enable us to read the ion chamber through the TV monitor. The collimator is set for larger field size (35 cm x 35 cm) and the 115 .9: Cobalt teletherapy machine. measured at a distance of 1 m from the source. below floor and patient weighting area etc. the exposure rate measurements are repeated for different gantry positions of 90. The ion chamber position is changed to different locations around the head at the same 1m distance from the source. all four sides. Primary Barrier Adequacy This survey will revel and ensure the shielding adequacy of the primary barriers. 5. The gantry is kept at 0 degree position.10: Cobalt teletherapy machine. to cover the ion chamber location. leakage exposure Radiation Survey: Exposure rate measurements in mR/h. The occupancy around the installations.1 % of the useful beam dose rate. The machine is switched on and the ion chamber reading is noted. Radiation survey. Radiation Monitoring Fig. door. 5. Now the unit is switched ON and the exposure rate is measured by using a wide range ion chamber survey meter. Area Survey The sketch of the teletherapy installation is drawn on a paper. The readings are tabulated as shown in the case of linear accelerator. Mark number of locations in the drawing. above ceiling. Similarly. The readings in exposure rates (mR/h) are noted for at least 8 locations around the head. The CCTV camera is positioned. It is repeated to complete the measurements in all the locations. . Date: . Textbook of Radiological Safety gantry is kept at 90 degree...... The measured readings are tabulated as shown in the Table 5.... The measurements are recorded as follows (Table 5.11........ Similarly..........................11: HDR Brachytherapy system: OFF position leakage measurements ........................5): Table 5. measurements are made by focusing the beam towards ceiling and basement if any.... Measurement A B C D E F G H Mean position Primary wall 1 Primary wall 2 Above ceiling Below floor HDR Brachytherapy Survey The high dose rate Brachytherapy equipment require radiation protection survey measurements for both source OFF and ON condition................. When the source is in OFF condition.6....... Now the beam is focused towards the primary wall 1.... A wide range survey meter of ion chamber type can be used to perform the measurements... 116 Fig... 5.......... the leakage radiation levels in mR/h is measured both at 5 cm from the surface of the treatment head and at 1 m from the center of the treatment head at various positions as shown in the Fig........The exposure rate behind the barrier is measured by using the ion chamber survey meter... 5.5: Measured exposure rate in mR/h Survey meter: Wide range ion chamber Make: .............. Model: ........ Then the gantry is set at 270 degree and the exposure rate is measured behind the primary wall 2.............. .......... Activity: .................... Table 5.................................... Make: . .7: Radiation levels during source ON condition Survey meter: ......7. μSv/hr 1 13 ..... ........ Model: . 12 16 Table 5.......... Make: ... Date: ..... The readings are tabulated as shown in Table 5...... They should be periodically checked to confirm that reliable readings are indicated........... ...... Model: ..... by comparison of the recorded reading with the check reading made at the same distance from the radiation source.................. CALIBRATION AND MAINTENANCE OF RADIATION MONITORING INSTRUMENTS Radiation monitoring instruments should be kept in good working condition... μSv/hr 1 .............. If the check reading after corrections varies considerably...............6: Radiation levels at 5 cm and 1 m during source OFF condition Survey meter: . The simplest method of checking the instrument performance is to use the instrument just after it has been calibrated by the manufacturer and to record for future reference..... Positions 5 cm from the source Positions 1 m from the centre of the housing.... mSv/hr source housing........... .......... Position Radiation levels.. Date: ....... In addition. after making necessary corrections for radioactive decay of the radiation source................ Performance check can then be made at any time................. by simulating the HDR treatment with out patient...... Various locations are selected in and around the HDR installation and radiation levels are measured by using the above survey meter....... the exposure rate at a specific distance from a radiation source of known strength... 10 117 .............. They should also be checked after any servicing or repairs........... ..... Radiation Monitoring Radiation survey measurements are also carried out when the source is in ON condition......................... .................. Activity: ........... the instrument should be got serviced and recalibrated by the manufacturer............................ the operational and handling instructions should be scrupulously observed to ensure prolonged and trouble free performance of the instrument.......... The Physics of Radiation therapy. Jerrold TB.) Lippincott Williams & Wilkins 2002. Lippincott Williams & Wilkins 2004. 4. John MB. The essential physics of medical imaging. Basic radiological physics. Textbook of Radiological Safety BIBLIOGRAPHY 1. 3. Ramesh C. Jaypee bothers medical publishers P Ltd.). (2nd edn. (3rd edn. 118 . Lippincott Williams & Wilkins 2003. New Delhi 2001. Nuclear medicine physics. Edwin ML. Instructions to High dose rate Brachytherapy users: Nucletron India (P) Ltd. Seiber JA. Khan FM. 5. Thayalan K. 2.). Chennai. (5th edn. The parameters which affects the image quality are applied tube voltage (kVp). QUALITY ASSURANCE FOR DIAGNOSTIC RADIOLOGY The goal of QA in diagnostic radiology is to obtain optimal image with minimum radiation dose and at minimum cost. which may leads to repeat examination (retake). tube current (mA). The radiologists may not be able to extract diagnostic information from the radiograph. A Radiological image may be good to look. congruence of optical and radiation fields and Focus to film distance (FFD). The QA should be organized as a program which includes the staff training. team work is essential for achieving good quality. and the American Association of Physicists in Medicine (AAPM) have recommended QA programs for Radiological practice. focal spot size. It is designed specifically for an institution to meet those standards. due to proper density and positioning. Professional organizations like American College of Radiology (ACR). (ii) Nuclear medicine. equipment and facility. systematic QA programs are to be developed and implemented in all diagnostic X-ray facilities. This is policies only by proper evaluation of the radiological equipment. The QA programs are developed for a specific application and the following paragraphs will explain the QA procedures related to (i) Diagnostic radiology. This will enable us to monitor periodically the performance of the X-ray unit. The objective of quality assurance program is a systematic monitoring of the quality and appropriateness of patient care. physical and technical aspects and hence. staff and public. then its image quality is not assured. The general criteria of standard of quality is set by the profession collectively. To achieve the above goal. time of exposure (s). Retakes result in unnecessary radiation dose to patients. If it do not reveal anatomic details. contact between film and screen. . clinical. increase the workload and cost. beam alignment. and (iii) Radiotherapy. The implementation of QA involve administrative. film processing conditions and viewing conditions etc. Chapter 6 Quality Assurance INTRODUCTION The term quality assurance (QA) describes a program that is designed to control and maintain the standard of quality set for that program. QA is essentially a set of policies and procedures to maintain the quality of patient care. In medical use of radiation. Table 6. Tube housing leakage The various tests. and (v) repeat the QA again. Textbook of Radiological Safety The quality assurance (QA) program begins with performance evaluation tests of the X-ray unit at the manufacturing site. or to determine that repairs or modifications have improved recent improper performance. their frequency and tools required Test Frequency Test tool kVp Once in 3 years KVp meter Timer Once in 3 months Spinning top /KVp/ timer meter and dose measuring meter Out put. The reasons to test the imaging equipment are to observe the equipment performance at installation in order to determine that it is working properly. the control panel display/indicators and the tube housing details are checked initially and it is followed by the set of tests listed below. (iv) take corrective and preventive measures. Every QA program involves the following steps that includes (i) performing the QA tests. Central beam alignment 3. (ii) record the results. Timer check 6. Focal spot size 4. Tube voltage (kVp) 5. to determine that it is currently working as well as it did at the time of installation.1. their frequency and the tools required for each test are summarized in the Table 6. Out put consistency 10. with and optical field Annually and whenever screen film cassette Grid alignment film density appears Grid alignment test tool 120 nonuniform . Congruence of Radiation and optical fields 2. Total filtration 7. QUALITY ASSURANCE FOR RADIOGRAPHY UNITS 1. In general the mechanical characteristics. (iii) analyze the result.1: QA tests. Linearity of mA loading stations 8. Timer linearity 9. Then QA tests are carried out at regular intervals and also after every major repair. mR/mAs Monthly Dose measuring meter Inherent filtration Once in 3 months Dose measuring meter and aluminium absorbers Focal spot size Once in a year Focal spot test tool with non- screen film cassette Central beam alignment Once in 2 months Beam alignment test tool with screen film cassette Congruence of radiation Once in 2 months Collimator test tool. followed by acceptance tests after the installation is completed. Y′) between the edges of optical and radiation fields are measured (Fig.1A and B: (A) Setting of the Beam alignment and Collimator test tool. It should be within 2% of FFD. The film is then exposed under suitable kV and mAs (Fig. This test tool consists of a fibre glass board of size 24 cm x 27 cm with a rectangular area 20 cm x 16 cm marked on it by coating of X-ray opaque material. 121 (B) Congruence of radiation and optical fields .1B). Focus-to-film distance (FFD) is kept as 100 cm. which enable the use of this test-tool in conjunction with the beam alignment test-tool. If the optical field and radiation field are not congruent. 6. Two concentric circles of radii 4 mm and 8 mm are engraved in the centre. the shifts (X. The collimator test-tool is used for testing the congruence of optical and radiation fields. to obtain the shift of fields directly in terms of percentage of FFD. Quality Assurance Congruence of Radiation and Optical Fields The optical field in the X-ray equipment is used for defining the radiation field and to limit the same only to the area of clinical interest on the patient. The light field is adjusted to coincide with the rectangular area marked on the test-tool. The collimator test-tool is kept above a screen type cassette. loaded with a medium speed X-ray film is placed on the table. 6. This rectangular area is divided into four equal segments by two graduated perpendicular bisectors.1A) and developed. X′. The difference in the dimensions of the optical and radiation fields (A) (B) Figs 6. From the radiograph. A screen type cassette. the area of clinical interest may be missed in the radiograph leading to retake and unnecessary radiation dose to patients. Procedure The table is kept horizontal with the help of a spirit level. Y. If the beam alignment is perfect. If it falls between the images of inner and outer circles.50 to 30 from the perpendicular. Textbook of Radiological Safety (X+X′. Beam alignment test is usually carried out along with the test for congruence of optical and radiation field. the central ray of the beam is within 0. the procedure for the congruence of optical and radiation field is repeated. This may result in loss of minute details. the central ray lies within 1. Tolerance for the beam alignment is 1. Since. If grid is used. The difference between the sums of the length and width of optical and radiation fields are also computed. The tolerance should not exceed 4% of FFD.5 cm and length 15.5° (Fig. If the image of the top ball falls within the image of the inner circle. detail) in a radiograph depends on the focal spot size. the image of the top ball will merge with the image of the ball at bottom. It should be within 3% of FFD. If the images of the two steel balls overlap.2A to C: Interpretation of the image of the two steel balls in the beam alignment test tool Focal Spot Size 122 The ability for resolving the smallest size of the image (i.2). the focal spot size may be .e. The film is exposed and processed. Stainless steel balls of diameter 1. the image may be distorted. The beam alignment test tool is kept on the collimator test-tool such a way that the stainless steel ball of the lower side of the tool is just above the center of the collimator test-tool. the distortion will be magnified resulting in total loss of minute details. outer diameter 7. (A) (B) (C) Figs 6. To do this.6 mm are co-axially fixed at the centre of both these discs.Y+Y′) are also recorded. The deviation of beam from the perpendicular is determined from the location of the image of the top steel ball in the circles in the radiograph. the central ray is within 1.2 cm. The test tool consists of a clear transparent acrylic cylinder of inner diameter 6. Central Beam Alignment If the X-ray beam is not perpendicular to the image receptor.3 cm. The beam alignment can be tested using a beam alignment test tool. Acrylic circular discs.50. each of 6 mm thickness are fastened on both sides of the cylinder.5 0 from the perpendicular. 6. Bar/hole test pattern is employed for evaluating focal spot by minimum resolution. for a magnification of 4/3 Smallest group lp/mm Effective focal resolved spot size (mm) 1 0.3 9 3.83 1.36 1.2: Effective focal spot size.14 2.19 3.5 8 2. which is the length of test-tool).0 cm diameter and 15 cm height. Focal spot size is evaluated using the focal spot test tool based on the principle of minimum resolution.1 10 4.84 4.7 123 . Magnification is calculated as the ratio between focus-to-film distance and focus to object distance (60/45 = 4/3).9 11 4. The focal spot size values quoted in the reference Table 6.66 0. are computed for a magnification of 4/3. Quality Assurance altered as a result of bombardment of electrons on the target. In this condition.8 7 2. the focal spot size (f) is related with line width and magnification (M) as follows: ⎡ M ⎤ f=⎢ ⎥ × line width ⎣ ( M − 1) ⎦ The test-tool consists an acrylic hollow cylinder of about 6.3 2 1. it has to be checked periodically to ensure that focal spot size is within acceptable limits. The sizes and spacing of the slits in these groups decreases by steps of 16% from 0.00 1. the edge gradient (penumbra) of one pattern of the pair overlaps with the image of other and the images of both the patterns of the pair cannot be resolved separately. The bar test pattern consists of 12 groups of lines (slits) of sizes gradually reducing in dimensions.00 3.2.6 5 1.8 12 5.7 3 1. This magnification is effected by maintaining the focus to film distance as 60 cm so that the test tool kept on the image receptor will have test pattern at 45 cm from the focus (60 cm -15 cm.76 0. At minimum resolution.1 4 1. An acrylic circular disc is fastened on one end of the cylinder.2 6 2.84 line pair/ mm to 5. Table 6.00 0. Each group consists of six lines arranged such that a subgroup of three parallel lines is perpendicular to the other sub-group. Bar patterns engraved on tungsten plate is mounted on this circular disc.38 1.68 2.6 line pair /mm. 2. digitally corresponding to a particular ratio of either analog or digital signals. The kVp meter. The FFD is kept at 60 cm (Fig. The vertical and horizontal groups give vertical and horizontal dimensions of the focal spot. Corrections for beam filtration should 124 be applied if necessary. The tool is placed over the cassette so that the vertical patterns are within the anode to cathode direction. A ratio circuit with analog digital circuit (ADC) or a micro processor software system displays the peak kilovoltage. 6. When exposed to radiation. Textbook of Radiological Safety Fig. the ratio of the signals produced by these detectors will be proportional to the peak tube voltage. The bar pattern on the radiograph is observed and the smallest group in which all six bars (both vertical and horizontal) are clearly resolved is identified. Tube Voltage The applied kilovoltage (kVp) affects the quality and quantity of X-rays reaching the image receptor. This method is instantaneous and direct reading. The film is exposed and processed. If there is a variation in the the kVp setting. Minimum resolvable line pair size and the corresponding focal spot size can be obtained from the Table 6. This in turn influences the contrast and density of the radiograph. Hence it is necessary to check the kVp settings periodically. Nonscreen technique is necessary to avoid blurring of images of test-pattern. . the focal spot test tool is placed on a nonscreen cassette loaded with film. it will affect the image quality. This can be done using a kVp meter. employs two solid-state detectors with different beam hardening filters.3).3: Bar test pattern for testing focal spot size and its image To carry out the test. 6. Hence. Fig.6. the rectangular cut portion is moving with the brass plate. mA and time settings.4). it will produce 100 X-ray pulses per second and the time taken for each pulse is 0. loaded with film. the spinning top is placed on a cassette. If it is a single phase full-wave rectified unit. The time taken for one pulse is 0. 6. Manual spinning top (for single phase half wave and full wave rectified systems only) and motorized synchronous tops (for single phase three phase and high frequency systems) can be used to test the accuracy of the timer. Quality Assurance The beam centered on the marked area on the top cover of the kVp meter. For a set time. the film receives exposure only when x-ray pulses are produced.02 s (1s/50). Proper distance is selected between the focus and the meter. The 125 . A single phase half wave rectified system produces 50 pulses/s and therefore 50 X-ray pulses are generated per second. Hence. The tolerance is ± 5kVp.5 s the half wave and full wave rectified unit emits 25 and 50 pulses respectively. the unit is energized. Since. The kVp meter reading is noted. Similar measurements are taken for different kVp settings. Timer Checking If the exposure time set on the diagnostic X-ray unit is not optimal. The variation between the set kVp and the measured kVp is found. the radiograph can be under exposed or over exposed. Spinning top consists of a rotating circular brass plate with a small rectangular portion cut (hole) at its periphery (Fig.01 s. there is a need to test the timer of the X-ray unit periodically. Then it is exposed for a given kVp. Production of X-ray pulses depends upon the rectification of the x-ray unit.4: Spinning top test-tool To check the timer. while the top is rotating. for a set time of 0. This may leads to repeat examinations. For a given kVp and mAs the dosimeter is exposed and the reading is noted. meters incorporating solid state detectors are available for the measurement of exposure time. which may appear as an arc of continuous trace of density. total filtration evaluation is necessary to verify whether the added filtration is adequate or not. the total filtration provided for the X-ray tube shall be optimum for patient safety and image quality. For this purpose regulatory bodies recommend total filtration requirement for X-ray machines for different maximum rated tube potentials. The pocket dosimeter is kept at the centre of radiation field of area 20 cm × 20 cm at a distance of 100 cm from the target.5 Total filtration includes the inherent filtration and the added filtration. The pulses passing through the hole of the circular plate. to cut off low energy components from X-ray beam. Total filtration of the X-ray tube is evaluated by determining the half value thickness of the beam. If the filtration is too high. Therefore. The HVT is measured for the maximum operating potential of the tube. Number of density patterns on the film Time = pulse frequency In the case of three phase and high frequency units. The low energy X-rays do not contribute to the image formation. synchronous spinning tops are used. Total Filtration All diagnostic X-ray units must have fitted with a minimum thickness of filter. Now a days. on the film. The speed of rotation (typically one rotation per second) of the disc is suitably selected. These units produce density patterns. In such cases. image contrast will be reduced. The measurement 126 is repeated and the average is obtained.5 mm is .5 70 to and including 100 2. Hence. produces equally spaced rectangular density patterns.0 Above 100 2. the angle subtended by the arc at the center of the image of the circular plate is measured with a protractor. but gives unnecessary patient exposure. Atomic Energy Regulatory Board recommends the total filtration requirements of X-ray diagnostic equipment as follows: Maximum rated tube potential (kVp) Minimum total filtration (mm Al) Less than 70 1. Textbook of Radiological Safety experiment is repeated to cover the entire range of the timer. by using a pocket dosimeter. An aluminum filter of 0. The spacing between the patterns depends upon the speed of rotation of the spinning top. The exposure time is calculated as the ratio of angle subtended by the arc to the total angle (360°). 12 3.2 3.28 2.5 0.4.76 0.4: HVT as a function of filtration and tube potential (three phase generators) Total Peak potential (kVp) filtration 60 70 80 90 100 110 120 130 140 (mm Al) HVT ( mm Al) 2.22 1.90 2.08 1.95 Table 6.08 2.86 3. The measurements are repeated 5 times.87 2.4 2.3 2. A pocket dosimeter and charger is used to measure the radiation output.5 1. Similar measurements are repeated for aluminum filters of thickness 1.70 1.3 3. For a fixed kVp and time an available mA station is selected.49 1.6 4.00 2. 1.67 0.00 1.9 4.34 2. For each measurement X (mR / mAs) is calculated.0 3.16 2. The tube is energized and the dosimeter reading is noted.82 3.70 2.33 1.58 1.95 2.48 2.16 2.40 3.90 2.62 2.90 2.6 3.59 1.5 2.75 1.1 3. Similar measurements are made by keeping the kVp and time constant.47 0.5 2.9 3.5 1.3: HVT as a function of filtration and tube potential (Single phase generators) Total Peak potential (kVp) filtration 30 40 50 60 70 80 90 100 110 120 (mm Al) Half value thickness (mm Al) 0. for other mA stations.6 3.3 4. The absorber thickness for 50 % transmission will be the half value thickness of the X-ray beam.30 3.10 2.58 2.86 3.40 2.0 1.16 1.36 0.46 1.70 1.42 1.49 1. 2.5.0 0.0 3.38 3.02 1.65 3.3 4. Table 6. 4 and 5 mm.0 0.0 4.55 0.95 1.58 2.04 1. The charged pocket dosimeter is kept at the centre of the radiation field of area 20 cm × 20 cm at a distance of 100 cm from the focus. 3.5 0.68 3. Transmission curve of the X-ray beam can be plotted on a graph between the absorber thickness and measured dosimeter readings.84 0.25 1.6 2.6 Linearity of mA Station The linearity of mA can be tested by measuring the radiation output of the machine.3 and 6.38 1.2 2.6 5.42 2. Quality Assurance interposed (at the collimator level) and the measurements are repeated.69 1.12 3.0 3.25 2.21 1.06 3.92 1.7 3. Total aluminum filtration could be determined from HVT using calibration Tables 6.37 2.3 3.82 1.58 0. to eliminate statistical variations.6 4.0 2. 127 .78 1.08 1.78 0.92 1.60 2. X max − X min The coefficient of linearity = X max + X min Coefficient of linearity should not exceed 0. The operating time should be greater 128 .5 s.5 s. by keeping mA and time constant. Linearity of Timer To test the linearity of timer. 1 ⎛ 1 ⎞ ⎡⎛ ( X − X ) ⎞⎤ 2 2 Coefficient of variation (COV) = ⎜ ⎟ ⎢⎜ ∑ i ⎟⎥ ⎝ X ⎠ ⎢⎣⎜⎝ ( n − 1) ⎟⎥ ⎠⎦ Coefficient of variation should not exceed 0. Output Consistency To test the out put consistency. the pocket dosimeter is used.1. Textbook of Radiological Safety X max − X min The coefficient of linearity = X max + X min The coefficient of linearity is evaluated. For each measurement The average and the X (mR / mAs) is calculated. which should not exceed 0. For each kVp the average dosimeter reading and the X (mR / mAs) is calculated. For a fixed mA and time an available kVp station (say 70) is selected and the tube is energized. The consistency at each kVp station is checked by evaluating the coefficient of variation. The dosimeter reading is noted and the measurements are repeated 5 times. the collimator of the tube housing is fully closed and the tube is energized at maximum rated tube potential and current at that kVp. The dosimeter is exposed to 50 kV.1.05. The dosimeter reading is noted and the measurements are repeated 5 times. Similar measurements are made for 1s and 1. the pocket dosimeter is used. Similar measurements are made for three more kVp. 200 mA and 0. Tube Housing Leakage The radiation leakage measurement is carried with an ionization radiation survey meter. at a distance of 100 cm from the focus. The charged pocket dosimeter is kept at the centre of the radiation field size of 20 cm × 20 cm. For checking the leakage radiation. The charged pocket dosimeter is kept at the centre of field size 20 cm × 20 cm at a distance of 100 cm from the focus. by keeping the kVp and mA constant. The maximum radiation leakage at 1 m from the focus. mAs : 20 (mA = ———...... Operating parameters: focus to film distance: 100 cm. Central beam alignment. leakage in 1 hour is computed by assuming workload as 180 mAmin in 1 hour.. The tilt in the central beam is —————° Tolerance: Tilt < 1.. cm % of TFD X′ = . The exposure rate at one meter from the target is measured at different locations (anode side.... Shift in the edges of the radiation field X = ... cm % of TFD Y + Y′ = . Quality Assurance Test Format 1....... cm % of TFD Y = ... cm % of TFD Tolerance : 3 % of TFD c. Difference between sums of lengths and widths of optical and radiation fields X + X′ + Y + Y′ = . kV : 50kV.. s = ——— ) a... Congruence of radiation and optical fields 2...... cm % of TFD Tolerance : 4 % of TFD d.... cm % of TFD Tolerance : 2 % of TFD b.. cm % of TFD Y′ = .min in one hour) / ( 60 min × Applied mA) The tolerance limit of leakage radiation at 1 m from the focus is < 115 mR in one hour.... Quality Assurance than the time constant of the survey meter.. cathode side.50 129 ..... for work load of 180 mAmin in 1 hour is calculated as follows: Maximum leakage = (X mR/hr × 180 mA.... Difference in the dimensions of the radiation and optical fields X + X′ = . From the maximum leakage rate (X. mR/h) for both tube housing and collimator... front back and top) from the tube housing and collimator................ Observe the images of the two steel balls on the radiograph and evaluate tilt in the central beam.. kVp:70.8 ≤ f ≤ 1.(15 mAs) Tolerance : ± 5 kV 5. mAs: 40 .5 mm (iii) + 0.3 f for f > 1. Tube voltage Operating parameters: Distance: 40 – 50 cm Applied kVp Measured kVp 60 kVp. mAs:40-50 (mA= 40-50. time = ————— sec Tolerance : ± 10 % of the set time 130 .8 mm (ii) + 0. Textbook of Radiological Safety 3. kVp: 70.4 f for 0. s = 1. time = ————— sec ————for (ii).6) (nonscreen film technique) Large focus size: Stated —————. ———— for (ii). (20 mAs) 120 kV.8 s Number of slit patterns on developed film: ———— for (i). Timer checking Operating parameters:Distance: 100 cm.mm × ——--mm Measured———--mm × ———mm Small focus size: Stated ———-—— mm × ———mm Measured ——-—-mm × ———-mm Tolerance: (i) + 0. (40 mAs) 80 kV. time = ———— sec. (25 mAs) 100 kV.5 f for f < 0. Arc measured : ——— for (i).80 Applied time: (i) 0.4 s and (ii) 0.5 mm 4. time = ———— sec. Focal spot size Operating parameters: Distance: 60 cm. 5 2. Quality Assurance 6. kVp : 60.5 1. Total filtration Operating parameters: Focus to detector distance: 100 cm kVp : 100. mA range Output Average mR/mAs 1 2 3 4 5 (X) 100 200 300 X max − X min The coefficient of linearity = (COL) X max + X min Tolerance : < 0.0 4. Linearity of mA loading station Operating parameters : Distance : 100 cm.0 1. mAs : 20 (mA : 100 .5 1.0 Total filtration = —————— mm of Al.0 mm Al for kVp ≤ 100 2.5 X max − X min The coefficient of linearity (COL) = X max + X min 131 Tolerance : COL < 0.1 8.5 mm Al for kVp ≤ 70 2. kVp : 50.5 3.5 mm Al for kVp > 100 7.2 s) Added filter Output Percentage (mm Al ) 1 2 Average transmission 0 0.5 5. Linearity of timer Operating parameters: Distance : 100 cm. Tolerance : 1.0 2. mA : 200 Time Output Average mR/mAs 1 2 3 4 5 ( X) 0.0 s. Time : 1.1 .5 4.0 1.0 3. Time : 0. ————— for ————-80 kVp. 1.5 s) (Maximum) (minimum) Back X-ray tube Left Right Collimator Front Location Exposure level (mR/h) (at 1.0 m Left Right Front Back Top from the focus) Tube Collimator Work load = 180 mA min in one hour (X mR / hr × 180 mA min in one hour) Maximum leakage = (60 min Applied mA) The tolerance limit of leakage radiation at 1 m from the focus is < 115 132 mR in one hour. . Textbook of Radiological Safety 9. Tube housing leakage Operating parameters: Applied voltage: ———— kVp.———— for —————120 kVp Tolerance : COV < 0. mAs : ————— ( ——— mA.05 10. ———— for ————-100 kVp. Output consistency Operating parameters: Distance : 100 cm Applied mAs Output (mR) Average mR/mAs kV (X) 1 2 3 4 5 70 80 100 120 1 ⎡ ( X i − X )2 ⎤ 2 ⎢∑ ⎥ ⎢⎣ n − 1 ⎥⎦ Coefficient of variation (COV) = X COV = ———— for ———— 70 kVp. Mammography test phantom can be used to optimize the techniques. 5 Aluminum oxide speck groups and 5 discs simulating masses . that simulates masses (Fig. and contains components that model breast disease and cancer in the phantom image. 6. thorough performance testing is necessary to determine the baseline values and to monitor with periodic quality control testing.5: Mammography accreditation phantom composed of a wax insert containing 133 6 nylon fibers. and an acrylic disk attched to the top of the phantom. Hence. Even a small change in equipment performance. The wax insert contains 6 cylindrical nylon fibers of decreasing diameter. Quality Assurance QA FOR MAMMOGRAPHY X-RAY UNIT Mammography requires careful optimization of technique and equipment.It is intended to mimic the attenuation characteristics of a standard breast of 4.5). It is composed of an acrylic block. It simulates the radiographic characteristics of compressed breast tissues. the compression needs to be calibrated and the Automatic exposure control device must be checked. film processing. or film viewing conditions can decrease the sensitivity of mammography. of decreasing diameter and thickness. In addition. and 5 low contrast disks. a wax insert. Fig.2 cm compressed breast thickness of 50 % adipose and 50 % glandular tissue composition. 6. The above mentioned tests for general radiography X-ray units can be repeated for mammography also. 5 simulated calcification groups (Al2O3) of decreasing size. patient setup. and 3 masses must be clearly visible. As per the recommendation at least 4 fibers. The optical density at the centre of the phantom image must be at least 1. Two more readings are taken and average is found in R/min. It should not be less than 30 cm. The number of mesh lines that are resolved is noted. for a workload of 180 mAmin. Image Intensifier Assembly Leakage A given kVp. at an average glandular dose of less than 3 mGy. High Contrast Sensitivity Wire mesh lines and bar strips are tested for resolution. which is clearly seen on the monitor is found. . The maximum radiation leakage level at 5 cm from the surface of the image intensifier (II) assembly is measured in mR/hr. mA and exposure time is selected. QUALITY ASSURANCE FOR COMPUTED TOMOGRAPHY Mechanical Tests Alignment of Table Gantry The congruence between the gantry midline and table midline is checked 134 using plumb line. The tolerance is 1. Textbook of Radiological Safety Identification of the smallest objects of each type that are visible in the phantom image indicates system performance. 3 calcification groups . Focus to Table Top Distance The distance between the focus to table top is measured in cm.5 lp/mm.2. The tolerance is < 5. A pocket dosimeter is kept on the table. The tolerance should be with in ± 5 mm. the resolved bar strips is noted. QA FOR FLUOROSCOPY X-RAY UNIT Table Top Exposure Rate The maximum kVp and mA is selected in the machine. Tolerance limit: A hole of 1/8” diameter. below the centre of the image intensifier (II) tube field. The unit is energized and the dosimeter reading is noted.7 R/min. The recommended limit for radiation leakage levels at 5 cm from the surface of image intensifier (II) assembly is 100 mR in 1 hour. Then the leakage level for 1 hour is calculated. In the case of bar strips. The tolerance is 30 lines/inch. Low Contrast Sensitivity The diameter of the smallest size of the hole. The kVp. mm Measured density width (FWHM) X-ray Generator Tests Measurement of Operating Potential The kVp meter is used to do this study. The difference between the set couch position and the measured is found. The alignment of the internal laser light and the external laser light is checked. i. full wave half maximum (FWHM) is found for each slice thickness. Collimator Test Radiation Profile Width A non screen cassette is used for this study. mAs and the slice thickness is selected. The tolerance should be with in ± 2 mm. The gantry is tilted for a set value and the corresponding tilt is measured. The tolerance should be with in ± 2 mm. say 1 cm. This is repeated for different slice thicknesses. A given kVp and mAs are selected. 2 cm. Quality Assurance Scan Localization Light Accuracy A non screen cassette loaded with film is used for this study. An initial table position is chosen (arbitrary) and a given load is put on the couch.. The tolerance should be with in ± 2 kVp. Now. A given mA station is selected on the scanner. This is repeated for different kVp readings. From the density profile. At the same time the couch increments are measured correspondingly. Later. a kVp is set on the scanner and the same is measured with kVp meter. For a given slice thickness the density profile is recorded on the film.e. The kVp. Gantry Tilt A non screen cassette loaded with film is used for this study. The difference between the set and measured gantry tilt is found. The tolerance should be within ± 1 mm. mAs and slice thickness is suitably selected. The table is set with different increments from the reference position. the profile width. 3 cm. 135 . Set slice thickness. and 5 cm respectively. A particular kVp and mAs is selected in the scanner. The tolerance should be with in ± 3° Table Position /Increment A non screen cassette loaded with film is used for this study. the mA station is changed and the measurements are repeated and the results are recorded as given below. 4 cm. 05 Resolution Low Contrast Resolution A low contrast resolution test phantom is used for this study. mAs and slice thickness is set on the scanner. The tolerance limit for coefficient of linearity is ± 0. The resolution is measured from the phantom in mm and the percentage of contrast difference is calculated. A given kVp.05 Output Consistency Follow the procedure described for the basic radiography unit.05 Measurement of Timer Linearity Follow the procedure described for the basic radiography unit. previously. The tolerance is 5. The phantom is positioned in .12 lp/cm at 10% contrast difference and the expected high contrast resolution is 0.5 % contrast difference.25 lp/cm. The size of the smallest resolvable bar /hole pattern is found in mm or lp/cm and the percentage of contrast difference is calculated. The phantom exposed for a given window width. A given kVp. The tolerance limit for coefficient of linearity is ± 0. previously.5 mm at 0. The phantom exposed for a given window width.0 mm at 1% contrast difference(minimum) and the expected is 2. The tolerance limit for coefficient of linearity is ± 0. Radiation Dose Tests Measurement of Computed Tomography Dose Index (CTDI) A pencil type ionization chamber with suitable electrometer is used in 136 conjunction with a head/body CT phantom. mAs and slice thickness is set on the scanner. The tolerance is 1.6 mm or 3. previously. Fix the mAs and slice thickness as constant and vary kVp and make measurements with pocket dosimeter or remote control exposure meter. Textbook of Radiological Safety Set kVp mA station 1 mA station 2 mA station 3 mA station 4 Measurement of mA Linearity Follow the procedure described for the basic radiography unit. using a high resolution algorithm. High Contrast Resolution A high contrast resolution test phantom is used for this study.8 mm or 6. (mGy/mAs) Peripheraldose. Quality Assurance the couch and the ionization chamber is inserted in it. This procedure is completed both for head and body phantoms. similar to that of clinical studies. the kVp is changed to 100. For a given slice thickness the axial dose and peripheral dose is measured in mGy. QUALITY ASSURANCE FOR NUCLEAR MEDICINE Quality assurance in Nuclear medicine is essential to ensure that the equipment is always performing to its specifications. The kVp is set as 80 for a mAs of 100.The tolerance is ± 20 % of the quoted value (expected) and the minimum is ± 40 % of the quoted value. and semi annual checks of other performance parameters. (CTDIW)= 1/3 (CTDTC) +2/3 (CTDIP) = mGy/mAs. the Joint Commission on the Accreditation of Health care Organizations (JCAHO). From the above the weighted CTDI is calculated . then mGy / mAs is arrived. and 140 with same mAs and slice thickness and the measurements are repeated. correction algorithm. US and the National Electrical Manufacturers Association (NEMA) guidelines form the basis for most of the QA tests. The type of QA program and acceptance testing guidelines vary with type of equipment and country. Then the axial CTDI and the mean peripheral CTDI is found. and correction circuitry on or off). Then. However. All the measurements must be taken under the same conditions (pulse height window width. A typical QA program involve daily measurements of flood-field uniformity. (mGy/mAs) (i) (ii) (iii) (iv) Mean peripheral dose CTDTC CTDIP Weighted CTDI. 137 . Measurement Head phantom Body phantom Axial dose. The mean of the peripheral dose is found for both head and body phantoms. weekly checks of spatial resolution and spatial linearity. Tube Housing Leakage Repeat the procedure followed previously for general radiography X-ray units. A point source Tc-99m is placed at distance equal to 5 × UFOV from the camera face. The test pattern with strip width of 1 mm is placed on the surface of the NaI (Tl) crystal housing. a 10 cm plastic is placed between the sources and collimator and the measurement is taken. Spatial Linearity Spatial linearity describes lack of spatial distortion. The typical values of intrinsic spatial resolution are 2. Profiles through the images of the line sources are taken at different locations across the gamma camera face and fitted to a Gaussian function. until the peak channel records at least 1000 counts. Two more measurements are made from the resulting images. The differential spatial linearity is the deviation of the measured distance between two slits from the actual distance. The count rate should be < 30. The counting rate is. to determine the FWHM and FWTM. 30000 . This will enable to record X and Y resolution. Two sets image are taken and recorded. rotated to 90 degree. Textbook of Radiological Safety QA FOR GAMMA CAMERA Intrinsic Resolution The intrinsic resolution is determined with out a collimator using a linearity test pattern. The typical resolution is 8-14 mm for Tc-99m. used for intrinsic resolution. The measurements are taken with two orientations of the test pattern.000 cps to avoid pile up related mispositioning. Images are acquired and profiles taken through the image of the line sources are fitted to Gaussian functions. It is a measure of the cameras ability to portray the shapes of objects accurately.5 mm. Uniformity This is studied from flood-field images acquired without collimator. and conditions.5 to 3. Again it is repeated with 5 cm plastic. The source consists of two 1 mm diameter line sources. placed 5 cm apart at a distance of 10 cm from the front face of the collimator. The UFOV is the field of view of the gamma camera after masking off the portion of the camera face affected by edge packing effects. placed behind the sources. This will provide linearity measurements for both X and Y directions. This require the slit pattern. The FWHM and FWTM (Full width tenth maximum) of the profiles are measured in both X and Y directions. Data are collected. To account scattering. by rotating the text pattern to 90 degree. The maximum deviation of the location of the slits from their true location will give the absolute spatial linearity. line source. Once again it is done for UFOV and CFOV conditions. System Resolution This measurement is made with collimator and should be repeated for each collimator. A Tc- 138 99m source is placed at a distance of 5 × UFOV. low refers the minimum count difference for any five consecutive pixels in the image. Counting Rate Performance Two Tc-99m sources are placed about 1. Counting rates are measured with both sources (R12) and with each individual sources. Max. count Min. Tc-99m source is suspended at a distance of 5 × UFOV above the camera face. The total activity is sufficient to cause 20% loss in the observed counting rate. with out collimator.5 m away from the camera face. It is usually reported in keV or in % energy resolution based on the photo peak energy. count + Min. namely R1 and R2. All measurements are taken in the same source geometry. relative to true counting rate.8 t Energy Resolution The energy resolution is measured with a flood illumination of the gamma camera face.8 R 20 % = ln 0. count Integral uniformity ( % ) = Max. count This is calculated for both UFOV and CFOV. Typical values are 8% to 11% for Tc-99m. The typical tolerance value is 2 – 4% 100 × ( high -low ) The differential uniformity ( % ) = ( high + low ) where high refers the maximum count difference. Then it smoothed with 9 point (3 × 3) smoothing filter with following weightings: 1 2 1 2 4 2 1 2 1 From this the Integral uniformity and differential uniformity are arrived as follows. 139 . The resulting pulse height spectrum is analyzed to determine the FWHM of the Tc-99m photo peak. Quality Assurance cps and there should be minimum of 4000 counts in each pixel of the image. The dead time (t) and 20% count rate loss (R20) are calculated as follows: ⎡ 2R 12 ⎤ ⎡ ( R 1 +R 2 ) ⎤ t=⎢ ⎥ ln ⎢ ⎥ ⎣ ( R1 + R 2 ) ⎦ ⎣ R 12 ⎦ 0. 90. The source is placed at 10 cm from the camera face. For example. In the case of multi headed systems. an image matrix of 64 × 64. System alignment. However. It is also necessary to measure the reconstructed image uniformity. QA FOR SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY (SPECT) Many of the above QA procedures described for gamma camera can also be used for SPECT.01% to 0. In SPECT. 180 and 270 degrees) for a point source placed off center in the FOV of the SPECT system. to provide the background. A second image is recorded for an equal imaging time with the source removed. medium energy collimator is tested with In-111 and I-131 is used for high energy collimator. all the heads should be accurately aligned in the axial direction. an image of a uniform cylinder is reconstructed with suitable attenuation and scatter corrections. may require about 41 million counts. To detect non uniformities of this order at least 10. Otherwise this may enhance the blurring and artifacts. A typical protocol involves N number of projection profiles at equal angle intervals over 360°. The low energy collimator is tested with Tc-99m. A solution of the radionuclide is placed in 10 cm diameter dish to a depth of 2-3 mm. System alignment errors can be measured by recording profiles from different projection angles (0. non uniformities can lead to ring (single head system) and arc (multi head system) artifacts. uniformities of 1% or better are desirable for gamma camera detectors used as SPECT. 140 For each projection the centroid (rcen. The sensitivity is calculated by drawing a circular region of interest (ROI) around the image of the dish and integrating all the counts in that region. which can be done similar to volume sensitivity measurements. Textbook of Radiological Safety System Sensitivity It is to be measured for each collimator. by using relevant reconstruction algorithms and filters. Hence. Flood field uniformity ii. ( counts in ROI − background ) Sensitivity (cps / Bq ) = time (s) × source activity (Bq ) The typical sensitivity is on the order of 1-1. In this. zcen) of the image of the point source .5 × 10-4 cps/Bq or 0. there are some special requirements as follows: i. The system alignment test verify the mechanical centre of rotation coincidence with the centre of rotation (COR) defined for the projection data (reconstruction).015 %.000 counts (Poisson statistics) are required per image element. If it is not correct additional blurring or ring artifacts may arise. The correction tools should not cause any artifacts. A drop of the solution was then used to produce three point sources. Using a source holder. Once in place. Transverse spatial resolution is calculated for each PS position as FWHM and FWTM of the resulting point spread function. by interpolation between adjacent pixels on the radial (vertical) and tangential (horizontal) profiles. Glass capillaries with an ID of 1 mm is used to contain the PS. (iii) x = 10 cm. (ii) x = 0 cm. Quality Assurance on the gamma camera face is determined. Where r and z are the radial and axial coordinate respectively. Acquisition time for each single acquisition was 1 min. The two sets of measurements are centred at two axial positions in the scanner FOV: in the centre and at one- quarter of the axial FOV (3. In discrete element systems.8 cm). the three point sources are aligned (axially) in the scanner FOV using laser lights. it is measured by imaging three 18F point source(PS). Two sets of EM measurements. y = 0 cm. y = 10 cm. QUALITY ASSURANCE FOR PET-CT Performance evaluation for Positron emission tomography (PET) [National electrical measurements association (NEMA) NU2-2001 (N-01)] protocol) Spatial Resolution It represents the ability of the system to distinguish between two points of radioactivity in an image. The average COR error and the Axial deviation error are given as follows: N ⎛ 1⎞ Errcor = ⎜ ⎟ ∑ rcen ⎝N⎠ n =1 ⎛1⎞ N ErrAX = ⎜ ⎟ ∑ z − z cen ⎝ N ⎠ n =1 where zcen is the point spread function (PSF) centroid in the z direction and z is the mean value of zcen. A solution of water and 18F with a concentration higher than 185 MBq/ cc is prepared. consisting of 20 acquisitions axially spaced at 0. Image reconstruction of the PS is performed for both 2D and 3D data (FOV 25 cm) and each of the three sources are visualized. y = 1 cm. 141 . smaller detector elements with higher stopping power for 511 keV have the best potential for providing high spatial resolution. The two sets of measurements are then repeated in 3D mode. An axial profile is derived from the number of counts in each slice against the slice number and axial resolution is measured as the FWHM and FWTM of such a profile. In NEMA-01 protocol. Radial and tangential resolutions (FWHM and FWTM) for each radial position (1 and 10 cm) are averaged over both axial positions. the three glass capillaries containing the PS are positioned in the the centre of the axial FOV of the scanner at: (i) x = 0 cm.5 mm are performed in 2D. The analysis is first performed for each plane. A solution of water and 18F with a concentration greater than 1. 2nd tube: ID 7. The phantom is then positioned at x=10 cm and y=0 cm with respect to the centre of the scanner FOV and 2D and 3D measurements are carried out following the same protocol as before (for x = 0 and y = 0). The diameters of each tube are: i. the LS. OD 12. Rj = R0 exp (– 2 μXj) where µ is the linear attenuation coefficient.4 mm ii. Raw data sinograms are used in the analysis of sensitivity. 4th tube: ID 13.7 mm iv. The intrinsic scatter function is a measure of the relative system sensitivity to scatter. an additional aluminium tube is added around the LS.9 mm. Count rates Rj (j=1. 5th tube: ID 16. 1st tube: ID 3. Using a phantom holder. The N-01 sensitivity phantom consists of five concentric aluminium tubes. The count rate in the absence of attenuation (R0) was calculated by extrapolating the resulting exponential attenuation curve to Xj=0. The LS is prepared by filling a polyethylene tube (ID 1 mm. regardless of the .0 mm. OD 19.6 mm.7 MBq/ cc is prepared.2 mm. In each subsequent scan (60 s each). 700 mm long and stacked one inside the other. The sensitivity for each plane is calculated by dividing the extrapolated R0 by the measured activity. OD 6. Scatter Fraction and Count Rates The scattering of annihilation photons leads to falsely positioned coincidence events. y and z axis of the scanner FOV. In the N-01 protocol. OD 9. a lower scatter fraction is more desirable. the LS is surrounded by the 5 aluminium tubes. so that during the last scan. A second set of measurements (five scans) are taken to estimate the sensitivity in 3D mode. 3rd tube: ID 10. For a given source 142 distribution.1 mm. OD 15.9 mm v. OD 3 mm) in the central 70 cm and activity is measured. inserted in the smallest aluminium tube. The five scans in each set of measurements are corrected for radioactive decay. the absolute sensitivity of a scanner is measured as the coincidence event rate per unit activity (cps/MBq) from sufficiently low activity line source(LS) suspended within the scanner FOV in the absence of attenuating media. Variations in design cause PET scanners to have different sensitivities to scattered radiation.5 mm iii. Total system sensitivity is calculated as the sum of sensitivity per plane over the 47 planes.4 mm. A set of five 2D EM scans are acquired. is centred along the x.5) are plotted versus the sleeve thickness Xj. Textbook of Radiological Safety Sensitivity The sensitivity of a scanner represents its ability to detect annihilation radiation. as long as the phantom. Only the final frames of the SF & CR test (when the random rate was negligible.3 mm). In both acquisitions. 22 EM frames are acquired. The phantom is a 20 cm diameter solid polyethylene cylinder with an overall length of 70 cm. Raw data sinograms are used in the analysis of the scatter fraction and count rates (SF & CR) test. y=0 cm and axially centred in the scanner FOV. Two tests are performed.5 cm from its centre. The phantom has a hole at 4. can be inserted to contain radioactivity. The Noise equivalent count (NEC) rate is calculated as follows: R 2 trues NEC = R trues + R scatter + kR random Two NEC rate curves were then generated. 2D and 3D data sets are reconstructed as for the count rate accuracy test of the N-94. with k=1 and k=2. In the hole a Teflon LS (ID 2. random coincidences are measured by the delayed event (DE) technique. 3D sinograms are rebinned by using a single slice-rebinning algorithm. which are measured at a sufficiently low counting rate that random coincidences. Scatter component is calculated as for the N-94 over a fixed FOV of 40 cm diameter. centred on the reconstructed images of the phantom. The T rate (Rtrues) is determined by subtracting the random and scatter rates from the total prompts event rate (Rtotal). Total events are the sum of the unscattered events and scattered events. A circular ROI (18 cm diameter) is drawn. respectively. The LS is filled in its 70 cm central part with a solution of water and 18F. Scatter fraction is calculated as the ratio between scatter component and total events. with an initial activity of 2.500s between each consecutive pair of frames. because correction techniques cannot compensate on the noise introduced by the unwanted events and can potentially add bias to the image. In both tests. The remaining 18 frames are acquired for 1. The resulting dead-time and random corrected true image count rate (R) 143 . dead time effects. In each test (2D and 3D). Frames 1 to 4 are acquired for 900 s with no delay between consecutive frames. Quality Assurance accuracy of the method for scatter correction. The scatter fraction (SF) is defined as the ratio of the scattered events to the total events. and pileup are negligible. in 2D and 3D. Accuracy of Corrections for Count Losses and Random The same data set as was acquired for the SF & CR test is used. which goes through the whole phantom. parallel to its central axis.664 MBq and 1.500 s with a delay of 1. The total counts rate within a 24 cm transverse FOV is determined as a function of the radioactivity decay. the phantom is positioned at x=0 cm. Data are reconstructed with all count rate dependent corrections (dead-time losses and random coincidences) applied. below 1%) are used to calculate the scatter fraction.776 MBq. 144 Twelve background ROIs (37 mm diameter) are drawn on the central slice .3.5 MBq. To simulate body activity from outside of the scanner FOV. six interleaved acquisitions (2D and 3D) are performed.3. Four of the spheres.2 cm. the LS of the external phantom is filled with an activity of 165. The phantom is filled with a solution of water and 18F (5.3 kBq/cc). A CT scan of the phantom is used for acquisition (140 kV. normalization.7 and 2. The IQ phantom contains six coaxial isocentre spheres with diameters of 1.0.2. the phantom used for the SF & CR test is positioned at one edge of the IQ phantom. is evaluated using a phantom simulating a human torso in size and shape. the phantom is positioned with the spheres both in the transverse plane and along the z-axis of the scanner FOV. Image Quality—Attenuation and Scatter Correction Accuracy It is desirable to compare the image quality of different imaging systems for a standardized imaging situation that stimulates a clinical imaging condition. In this. while the other two are used to simulate cold lesions. 2.7 cm. circular ROIs with a diameter equal to the physical size of each sphere are drawn on CT images and copied to PET images. 1. dead-time losses. Data were corrected for random coincidences. as well as attenuation and scatter correction accuracy. The cylinder is a cold insert with a density of 0. and the spheres with a concentration eight times higher than the background. Once filled.30 g/cc to simulate the lungs. The acquisition time for each 2D and 3D measurement is 8 min and 20s and 7 min and 19 s respectively. are used to simulate hot lesions. The residual dead-time error Δ is calculated as follows: % Δr = 100[1 – (R ÷ Rextrap)] where Rextrap is the linear function of the true count rate extrapolated from the low count rate (where dead-time and random coincidences rate are negligible). the scanners image contrast and signal noise ratios are tested under conditions that stimulate a clinical whole body study. A cylindrical insert of 5 cm diameter. geometry. In a second experiment. is also positioned in the centre of the phantom. based on a whole body examination designed to cover a 100 cm axial FOV in 60 min. Textbook of Radiological Safety was plotted as a function of activity concentration. to simulate a lesion to background (L/B) ratio of 8.7. These times are derived. 2. 1. In order to evaluate the hot and cold sphere contrast. For this test.0. For both the experiments (L/B=8 and 4). respectively. scatter and attenuation. 90 mA). using a slice overlap for 2D and 3D mode of 5 and 11 slices. 1. as long as the phantom. with diameters of 1.8 and 3. Overall image quality (IQ). radioactivity concentration in the hot spheres is such that the L/B is 4. 1. 13. orthogonality of table top long axis to imaging plane. an ROI of 5 cm in diameter is drawn (in each slice of the phantom) on the central cylindrical insert to assess the accuracy of the attenuation and the scatter correction. 17. Electromechanical Tests These tests include the congruence of gantry laser and imaging plane. Quality Assurance and on slices ± 10 mm and ± 20 mm from the central slice. and iv. Different parameters used to evaluate the IQ test are: i. The accuracy of attenuation and scatter correction (ΔA Clung). (ii) image quality. Detailed information are also available in AAPM report No. 39 (9). ii. The background variability (BVj). radiation and sensitivity profile widths and tests on X-ray generator. while ahot/abkgd is the ratio of the activities in the hot sphere and background. Performance Evaluation of CT Performance evaluation tests of CT includes (i) electromechanical. ROIs of smaller size (10. ⎛ SD j ⎞ BVj = 100 ⎜ ⎟ ⎜ C bkgdj ⎟ ⎝ ⎠ where SDj is the standard deviation of the background ROI counts for sphere j. localization of CT and pseudo CT centre. Finally. The cold sphere contrast (CC). The hot sphere contrast recovery coefficient (HC_RC). accuracy of table vertical and longitudinal movement. iii. are calculated as follows: HC _ RC = (C hot / C bkgd − 1 ) (a hot / a bkgd − 1) where Chot and Cbkgd are the average of the counts measured in the hot spheres ROI and the average counts in all background ROIs respectively. and (iii) radiation safety. ⎛C ⎞ CC = 1 − ⎜ cold ⎟ ⎜ C bkgd ⎟ ⎝ ⎠ where Ccold is the average of the counts measured in the cold spheres ROI. 28 mm) are drawn concentric to the 37 mm background ROIs. 145 . AAPM-TG 66 (10) recommendations. ⎛ Clung ⎞ ΔAClung = 100 ⎜ ⎟ ⎜ C bkgd ⎟ ⎝ ⎠ where Clung is the average counts in the lung insert ROI. 22. The exposed films are measured using film scanner with 0. For this purpose 0. Linearity of mAs for different kVp is verified by obtaining the product of dose and time at different mA and time settings. IMAGE QUALITY TESTS Image Uniformity and Pixel Noise A 20 cm x 2. 20 and 30 cm using 0.5 cm thick water phantom is scanned by using head scanning ptotocol.Image noise is determined using the 146 relation . timer accuracy(s). Radiation Sensitivity and Profile Widths A ready pack film placed horizontal to the table top and at the CT centre is exposed using all available slice thickness.mAs linearity and repeoducibility. Non invasive measurement of kVp for different mAs are performed using suitable meters and the method adopted by AAPM-39(9). CT center and pseudo CT center an arbitray point exactly 60 cm inferior from CT centre are localized using a commercially available laser calibration phantom. X-ray Generator Tests on the X-ray generator include evaluation of peak potential (kVp). 10. 5. This test is also used to quantify longitudinal table motion accuracy and orthogonality of table top longitudinal axis to the image acquisition plane.1 cm thick tranverse images are acquired at the mid plane of two parallel slabs of the phantom separated by 60 cm.1 cm slice thickness. Calibrations of table linear scales are verified by moving the table both vertically and longitudinally in steps of 1 cm using an independent measuring scale. These FWHM values represent the radiation profile widths. Table indexing accuracy and reproducibility are tested by irradiating a ready back film placed perpendicular to the scan plane. Image homogeneity defined as the edge-to-centre difference in mean CT number is than caculated. 3. 6 and 9 o’clock positions and at the centre of the phantom using system software. Mean CT number of water contained with in a circular region of 1 cm2 (400 pixels) is obtained at different locations corresponding to 12. Textbook of Radiological Safety Gantry and Couch Congruence of gantry laser with centre of imaging plane and gantry tilt accuracy are verified using ready pack film(Kodak-X-V) adopting the method described in AAPM -39(9). Independent verification profile width has to be done by using vendor supplied phantom.01 cm step size and the FWHM of optical density profiles corresponding to every slice thickness is obtained. under scanner control longitudinal spacing of 0. the weighted computed tomography dose index (CTDTw) is calculated. For detail procedures refer the QA test for CT scans in diagnostic radiology in this chapter. since it is not possible to complete the necessary quality control testing before the product’s use-by date. The employment of short lived radionuclides in radiopharmaceuticals posses problems in quality control testing. polypropylene. and CTm and CTw are the measured CT numbers of the subject material and water. The phantom consists of seven cylindrical inserts of different materials (air. The scan protocol is usually 1 cm slice thick. QA FOR RADIOPHARMACEUTICALS Introduction All radiopharmaceuticals administered to patients must have the safety. polystyrene. Low and High Contrast Resolution Repeat the procedure that are given for QA test for CT scans in diagnostic radiology in this chapter. Quality Assurance % of noise = (σ × CS × 100) μw where σ is the standard deviation of CT numbers of water within the region of interest. quality and efficacy required for their intended use. This makes it imperative to employ a range of quick validation techniques in order to test the final product. (µm and µw) are ⎣ ( CTm − CTw ) ⎦ the linear attenuation coefficients for the subject material and water respectively. 147 . CT numbers for all these materials are measured from the scan image using system software and compared with the standard value. axial mode with 80-130 kVp and 100 mAs. Radiation Safety The CTDI is measured on the surface and centre for both head and body phantom by using the CT pencil ionization chamber. perspex. backelite. ⎡ ( mm − mw ) ⎤ CS is the contrast scale defined as CS = ⎢ ⎥ . nylon and Teflon) which stimulate attenuation coefficient of various organs ranging from lung to bone. CT Number Linearity A CT number linearity test phantom is used and the phantom is scanned at 130 kVp with 1 cm slice thickness. Then. which can make their determination difficult. Radionuclide Purity Radionuclidic purity is defined as the percentage of the activity of the radionuclide concerned to the total activity of the sample. Radionuclide Activity It is necessary to ensure that the correct activity is administered to the patient. The situation most relevant to hospitals and clinics is the determination of levels of 99Mo in 99m Tc eluted from a generator. Continued satisfactory use of the product enables the user to build up confidence in the quality of the supplier. Information on the specifications that radiopharmaceuticals should meet is also available in national and international pharmacopoeias. this can readily be determined by a screening method since the principal gamma energy of 99Mo (740 keV) is much higher than that of 99mTc (140 keV). it is advisable to purchase materials from radiopharmaceutical manufacturers who might have performed the above quality control procedures on the materials they are supplying. It is always advisable to measure the vial before and after dispensing the radiopharmaceutical into the syringe. The sample is then placed . Fortunately. The difference between the readings gives a more reliable indication of the dispensed activity. To carry out QA one may require mass spectroscopy and nuclear magnetic resonance spectroscopy etc. which are not usually available in a hospital setup. target materials for use in nuclear reactors or cyclotrons. There is therefore a requirement for control of the dose calibrator to ensure its correct functioning and accuracy. and eluents and diluents used in the preparation of the final product. Testing the synthesis of non radioactive materials may require the use of analytical techniques such as infrared and ultraviolet spectroscopy. Accurate measurement must be taken place during the preparation of radiopharmaceuticals and the dispensing of individual doses. Textbook of Radiological Safety Control of Starting Materials One of the major aspects of quality control is the source and purity of the non radioactive starting materials. The total activity of a sample is 148 measured in the normal way in a dose calibrator. and the department should ensure that it has access to such facilities. If the product has been approved for marketing by an appropriate authority. adsorbents used in columns inside radionuclide generators. It includes components of kits for technetium radiopharmaceuticals. albeit at very low levels. the user department should have little or no testing to perform on it. All radioactive materials are likely to have some radionuclidic impurities. Hence. mass spectroscopy and nuclear magnetic resonance. Details of the synthesis and analysis of certain kits are provided in IAEA-TECDOCs 649 and 805. The levels of each species can be determined by scanning the stationary phase with a suitable detector or cutting it into sections and placing each in a counter. this may lead to confusion in the diagnosis and for therapeutic radiopharmaceuticals it can produce significant dosimetric problems. paper or thin layers of silica gel) and readily available mobile phases (e. For materials prepared in-house. and preferably rapid. and must be such that the various radiochemical species have different mobility’s. since in many of them only certain impurities (e. Most of the activity may remain at the point of application on the chromatography strip and thus be unresolved. Low radiochemical purities may lead to an unintended biodistribution of the radiopharmaceutical. For diagnostic agents. and the activity is remeasured using calibration factors supplied with the instrument. acetone and butanone). Suitable systems for a range of radiopharmaceuticals are given in IAEA-TECDOCs 649 and 805. the radiochemical purity of materials containing short lived radionuclides can be established prior to their administration. either totally from original materials or purchased kits. Quality Assurance inside a lead pot 6 mm in thickness. which attenuates virtually all the 140 keV gamma rays of technetium but only approximately 50% of the 740 keV gamma rays of 99Mo. saline.g. in view of the scale of the operation only small volumes of solvent are needed. to perform such that. The techniques can be carried out with very simple apparatus. for which further testing is not necessary. in an ideal situation. but the techniques must be reliable and simple. but this is not universally so.1% of Mo at the time of administration. A range of techniques is available for such determinations.g.g. radiochemical purity determinations are useful to establish the suitability of the final product. The determination should therefore be carried out on the first eluate of a generator and on other eluates as deemed necessary. Manufacturers will normally declare the radiochemical purity. for example with beakers or measuring cylinders as chromatography tanks. pertechnetate in Tc radiopharmaceuticals) migrate with the solvent. Radiochemical Purity The radiochemical purity is defined as the proportion of the total radioactivity of the nuclide concerned present in the stated chemical form. the limitations of these simple systems need to be borne in mind. Most pharmacopoeias have a limit of 0. The choice of stationary and mobile phases is determined by the nature of the radiopharmaceutical. For many radiopharmaceuticals the radiochemical purity will be expected to be greater than 95%. However. and any eluates that exceed this limit must not be used. It is then possible to calculate the amount of 99 Mo present and express this as a percentage of the 99mTc. The simplest and most widely used technique is that of planar chromatography. using suitable stationary phases (e. Alternative techniques such as electrophoresis or HPLC 149 . the hospital radiopharmacy can benefit from the resolving power of absorbents used in HPLC. Commercial manufacturers of radiopharmaceuticals use HPLC routinely. Very high levels of Al can be toxic to patients. The technique utilizes the separating power of adsorbent materials packed into stainless steel columns through which a solvent is pumped at high pressure. Chemical Purity In addition to the problems of ensuring the correct chemical purity of starting materials for radiopharmaceuticals. Aluminium can be detected by a simple colorimetric limit test. These can arise from alumina being washed off the columns used in Tc generators. for example of colloidal radiopharmaceuticals. different species can be selectively removed from the cartridge and. activity can be determined with a dose calibrator or other simple scalar. In addition. Metal impurities may reduce the efficiency of 111–In radiolabelling. Recent developments have included the introduction of cartridges containing the same absorbents used in HPLC. By using appropriate eluents. providing a sufficiently high radioactive concentration is used. where the trivalent Al cation can alter the surface charge of particles and lead to aggregation and hence an altered biodistribution. Thus. By comparing the colour obtained with a small volume of the eluate of a Tc generator and that from a solution containing a specified concentration of Al ions (generally 5 or 10 parts per million). but it is unlikely that such problems will arise from administration of a radiopharmaceutical. However. certain radiochemical species. Different radiochemical species are identified by monitoring the eluate from the column and noting the time at which radioactivity is detected. The most likely situation to be met in radiopharmacies is the presence of Al ions in Tc radiopharmaceuticals. but without the expense of the equipment required. using either a solution or indicator strips containing an Al sensitive marker such as chromazurol-S. lower levels can adversely affect radiopharmaceutical formation or stability. Textbook of Radiological Safety offer advantages in that they can give more precise information about the radiochemical nature of the species present. hydrolyzed reduced Tc in Tc radiopharmaceuticals. This technique has limitations in that the apparatus is expensive and may not be routinely available to hospital radiopharmacies. 150 . may be retained on the column used to achieve the separation and may not therefore be accounted for in the analysis. there are certain situations where the chemical purity of the final material can be affected by the process used in the preparation. for example. it can be determined that the Al content of the eluate is below the specified level and hence suitable for use. but which can be loaded and eluted with syringes. on occasions. However. The required level of protection can be achieved by viewing through lead glass screens or by using mirrors to view vials placed behind lead shields. Particle size can be determined by light microscopy. the chemical composition and hence biodistribution of DMSA complexes is affected by the final pH of the solution. The normal renal imaging agent must be maintained at a pH below 3. reagents and equipment is the best way to minimize contamination. since only small samples are needed.5 of a pH unit. For the majority of radiopharmaceuticals these limitations are not normally detrimental. The easiest method of determining pH is to use narrow range pH papers. The limitations of the method are that it is usually only possible to observe a limited number of particles and that prolonged observation subjects the eyes to an increased radiation burden. It should be pointed out that such techniques may not detect small amounts of particulate contamination and are not suitable for radiopharmaceuticals which themselves are particulate. If the pH rises. control of pH is essential to ensure they retain their original specification. These may not be readily available in hospital radiopharmacies. Papers are readily available from a variety of sources. With Tc compounds. kits. A particle size range of 10-100 mm is generally specified as being optimal. the material becomes colloidal and unsuitable for labeling reactions. These limitations can be overcome by reconstituting a macro aggregate kit with saline and observing nonradioactive particles. Particulate Contamination Products for parenteral administration should be free from gross particulate contamination. Quality Assurance Determination of Particle Size Lung imaging agents are normally based on macro aggregates of human albumin.5.5. Some pharmacopoeias state that there should be no particles larger than 150 mm. using a graduated slide to ensure that there are no oversize particles and that a suitable range of sizes is present. particles can be present in the final solution as a result of coring of the rubber stopper if it is repeatedly punctured. Control of pH For some radiopharmaceuticals. Assessment of pH is subjective and such papers are normally only accurate to about 0. Colloidal particles cannot be visualized by normal light microscopy and. 151 . For example. The use of clean glassware. more elaborate techniques such as light scattering or membrane filtration will have to be used. while ensuring that adequate measures are taken to protect the eyes. indium (111In) chloride must be maintained at a pH of 1. Control can be exercised by visual inspection of the final radiopharmaceutical. in situations where it is important to know the particle size distribution. Commercial manufacturers frequently use the limulus lysate test in the control of their materials. Ongoing Evaluation of Product Performance Diagnostic radiopharmaceuticals of appropriate quality should have a 152 defined biodistribution within patients. and can be performed earlier. these objectives can be achieved by the use of a suitable sterilization technique during preparation of the radio- pharmaceutical. Sterility testing of radiopharmaceuticals present difficulties and it is often impracticable to apply tests described in pharmacopoeias. This rarely occurs with radiopharmaceuticals and hence the test is not usually performed in hospital radiopharmacies. If such observations are made . as is the case with Tc radiopharmaceuticals. having started with sterile materials (e. It can then be incubated in the normal way. this is not only because of the radioactive nature of the material but also. Alternatively. because the batch may consist of a single container. kits and generator eluate). This introduces serious problems with sample sizes and makes the test statistically unsatisfactory. a more satisfactory technique to ensure sterility of aseptically prepared radiopharmaceuticals involves staff simulating exactly the preparation techniques using culture media. Such tests have the advantages of being more sensitive and of using non-radioactive materials. the culture medium can be added to the remnants of the kit vial at the end of the working day. particularly if materials of animal origin are used in the preparation. In view of these limitations. for Tc radiopharmaceuticals. Control of the environment in which such manipulations take place is important. Textbook of Radiological Safety Sterility and Apyrogenicity Radiopharmaceuticals administered parenterally need to be sterile and apyrogenic. Inevitably this means that the result of the test is only obtained retrospectively. it may be prudent to assess the apyrogenicity. If a hospital is involved in the development of new agents. The use of the limulus lysate test for pyrogens is now becoming widely accepted in preference to the rabbit test. there is evidence that microorganisms do not survive in Tc radiopharmaceuticals.g. Determination of the apyrogenicity of injections is currently required only when the volume administered exceeds 15 ml. it is often necessary to use an aseptic technique to prepare the final radiopharmaceutical. As a compromise it is probably better to withdraw a small sample of the radiopharmaceutical whilst it is still active and place it in a suitable culture medium that can be shielded until decay has occurred. Although. In addition. but rigorous controls must be used to validate the test. and hence allowing them to decay in order to make testing easier can reduce the value of the test. The vial is kept shielded until inactive and then incubated. an adverse reaction may occur in a patient to whom a radiopharmaceutical has been administered. confidence in the quality of the materials being administered to patients is gained. may be necessary. as such. This 153 . The prevalence of such reactions has been estimated as 3 per 105 administrations and. If this occurs on a regular basis with different batches of the same radiopharmaceutical. and hence symptomatic treatment with an antihistamine is sometimes beneficial. as necessary. SUMMARY Each department needs to have its own quality assurance program to ensure that the products administered to patients are of the desired quality. It is worth trying to determine the cause of the problem. departments might not encounter a similar situation for many years. On rare occasions. adverse reactions that do occur are generally mild and self-limiting and do not require extensive treatment. This does not mean that the product is necessarily defective. The adverse reaction most commonly encountered involves the development of skin rashes a few hours after administration of 99mTc bone imaging agents. it can provide useful information for future reference and to prevent misdiagnosis occurring. the problem is likely to lie with the product. to national authorities. including administration of adrenalin. action is necessary to eradicate the problem. it is not acceptable merely to rely on the biodistribution in patients as the only quality control testing to be performed. thereby enhancing the quality of patient care. Departments can then be prepared to deal with such events if they occur. Quality Assurance regularly. In situations where an unexpected biodistribution is seen in one patient but not in others who received the same product. unexpected biodistributions are sometimes observed and may result from problems with the radiopharmaceutical. This may involve review of the methods used in preparation or a change in purchasing patterns of materials. or alternatively may be due to the patient’s condition or even the medication the patient may be taking. they should be reported to the manufacturer of the product and. Since the occurrence of such events is so low. However. If the problem has occurred with all patients who received that particular batch of radiopharmaceutical. In this way a database on the possible reactions that can occur is developed and information can be disseminated. Fortunately. An example is the visualization of the stomach in patients undergoing bone imaging with a technetium phosphonate complex. This indicates the presence of pertechnetate in the radiopharmaceutical and may have arisen as a result of an incomplete reaction when preparing the kit or of instability after preparation. If this can be identified. a patient related cause might be responsible. Histamine release in the patient is frequently implicated as the cause of the problem. When nuclear medicine images are reported. There are occasions when a severe anaphylactic reaction can occur immediately after administration and prompt action. Some of the basic QA parameters and procedures are given below. known as acceptance testing and repeated periodically. from a commercial manufacturer or prepared in-house) and the facilities used for the preparation. However. The tolerance for symmetry error is 1 mm. The procedure is repeated for the second jaw. One vital component in the assurance of quality of products is to have well trained competent staff who have the necessary skills and knowledge to deal with radioactive pharmaceutical products. warning lights and emergency lights. This will also ensure that the fundamental parameters have not changed since last measured. area survey and test of interlocks. QA FOR LINEAR ACCELERATOR Radiation Survey Radiation protection survey involves the measurement of head leakage. record keeping and quality control testing protocols. Jaw Symmetry To study jaw symmetry. a machinist’s dial indicator is used. In addition. The survey is evaluated on the basis of clinical use. it is important that the results obtained are reviewed and acted upon where necessary in order to maintain the quality of the products. by taking into account the workload.g. The feeler of the dial indicator is made to touch the face of the one of the jaws and the indicator reading is noted. First the gantry is set at horizontal and jaws open to a large field size. The detail procedure of survey is explained in chapter five under area survey. Now the collimator is rotated to 180 degrees and the feeler is touching the opposite jaw and the dial reading is again noted. The symmetry error is ½ of the difference in readings. Spirit level is used to check the collimator angle. QUALITY ASSURANCE FOR RADIOTHERAPY Quality assurance (QA) is the method of subjecting the newly installed equipment to an exhaustive performance testing to determine that the equipment is meeting the vendor’s technical specifications and hospital’s clinical specifications. These will be influenced by the range of products prepared. 154 . Usually the QA tests are performed at the time of installation. The periodic QA will ensure the integrity of its basic physical and functional specification through time. The difference between the two readings is noted. Textbook of Radiological Safety requires the development of appropriate documentation systems. individual hospital has to devise their own QA methodology and periodicity to suit their machine and model. use factor and occupancy factors. the source of the starting materials (e. The collimator is rotated to 90. Light Beam Axis and Cross-hairs Coincidence Gantry is set at vertical and the SSD is set at 100 cm. intersection of diagonals and the position of the cross hairs images. The procedure is repeated for a collimator angle 90.6). The gantry is rotated to 90. Check the coincidence of light field edges. The light beam is made on and the light field edges and the centre is marked with lead wires or radio opaque markers. A field size of 10 cm x 10 cm is set and collimator angle is set to 0 degree. The tolerance of the isocenter is ± 1mm. The film is exposed so that a optical density of around 1 is achieved. A plastic (2-5 mm) sheet is placed over the film pack to give electronic buildup and eliminate electron contamination. Optical and Radiation Beam Congruence A therapy verification film back is placed on the couch with SSD of 100 cm. 6. With the pointer extended. Now the pointer tip position is marked on the graph sheet. The stand should be kept away to avoid gantry collision. Gantry Rotation In the above procedure. A graph paper is fixed on the couch and the field size is kept as 10 × 10 cm. The tolerance of the isocenter is ± 2 mm diameter. If there is a misalignment it should be adjusted to bring down to coincidence.180 and 270 degree and each time the pointer tip position is noted. A sharp edge or wiggler may be attached to the end of the pointer rod to have effective observation. 155 . The coincidence of the optical and radiation beam is checked visually or by cross beam optical density profiles (Fig. intersection of diagonals and position of cross hair images. 180 and 270 degrees.180 and 270 degrees and the displacement between front pointer tip and the horizontal rod tip is observed. The horizontal rod tip and the front pointer tip are made to coincidence at 100 cm SAD with gantry position of 0 degree. The tolerance is ± 3 mm. another horizontal rod with fine pointer is positioned by means of a stand. Mechanical Isocenter Collimator Rotation A graph sheet is fixed on the couch and front pointer is put on the accessory mount with a gantry angle of 0 degree. Switch on the light field and mark the edges of the light field. Rotate the collimator through 180 degrees and mark the above parameters in the graph paper. Quality Assurance Coincidence Collimator Axis. the SAD is set to 100 cm. which will show clearly the intersection point. A slit beam is created by moving the jaws optimally. A ready pack film is kept flat on the couch. The procedure is repeated for upper jaws of narrow slit. This means that the plane of the film should be perpendicular to the plane of the couch top.7).8). The developed film will show the star pattern with dark centre region (Fig. A build up sheet is placed over the film and it is exposed to create a density of about 1. The lines should intersect with in a ± 2 mm diameter circle. . The upper jaws are fully opened and the lower jaws are closed to have a narrow slit of beam. while the lower jaws are wide open. 0 degree with a SAD of 100 cm. The lines should intersect with in a ± 2 mm diameter circle. Using a film marker lines are drawn through the middle of the slit images. Gantry A ready pack film is sandwiched between two plastic sheets and it is kept on the couch vertically. parallel to the gantry axis. Textbook of Radiological Safety Fig. 6. The collimator is rotated to different angles (4-8 angles) and each time the film is exposed. 6. The film is exposed for different gantry angles (12 to 30 degree) and the final star pattern is obtained 156 (Fig. 6.6: Optical and radiation field field congruence: 9 MeV electron and 6 MV photon beams (For color version see plate 1) Radiation Isocenter Collimator The gantry is set to vertical. First the one half (region 1) of the field is exposed. Fig.1981). 6. To check the beam misalignment a split field test is recommended. The gantry is rotated through 180 degree 157 . This may be due to (i) focal spot displacement. and (iii) displacement in the collimator rotation axis or the gantry rotation axis (Lutz et al. 6. A ready pack film is sandwiched between buildup sheet and is exposed twice. 6.9).7: Mechanical isocenter verification: Collimator rotation Isocenter shift by Isocenter shift by gantry rotation table rotation The shift is found The shift is found to be with in 2 mm to be with in 2 mm Fig. The lines should intersect with in a ± 2 mm diameter circle. A final star pattern is obtained and it is examined (Fig. (ii) asymmetry of collimator jaws. Quality Assurance Table The above procedure is repeated.8: Mechanical isocenter Fig. The table is rotated (4-8 times) to different angles and each time the film is exposed.9: Mechanical isocenter verification: Gantry rotation verification: Couch rotation Multiple Beam Alignment Check When more than one beam is used misalignment may occur. The gantry and the collimator is in fixed position. 6. by blocking the other half (region 2). Photon Beam Data Energy Photon beam energy is specified by the depth dose distribution. at 10 cm. The relative shift of the two images is the indicator of the misalignment. Usually the profile is folded at the centre and hence the two peripheral halves should be compared at the reference depths. The flatness should be checked for 10 cm and Dmax depths. Electron Beam Data Energy The electron energy is specified by practical electron range (RP) and the 158 most probable energy (EP)O as per AAPM-TG 25. The acceptable difference is ± 2 % from the published data. It is given by the relation: M−m F= × 100 M+m where M and m are the maximum and minimum dose values in the central 80% of the profile. The recommended depth for depth ratios are 10 and 20 cm. A central axis depth dose curve measured with a suitable ion chamber in a water phantom can be compared with published data (BJR 25). The RP is the depth of the . for maximum field sizes. cross plane and diagonal directions and checked for flatness for each given field size.100 SSD. Field Flatness Field flatness for photon beams is defined as the variation of dose relative to the central axis over the central 80 % of the field size at a depth of 10 cm in a plane perpendicular to the central axis. to minimize displacement correction. The AAPM -TG 45 specified flatness in terms of maximum percentage variation from the average dose across the central 80 % of the width at half maximum (FWHM) of the profile in a plane transverse to the beam axis. Beam profiles are generated for inplane. The acceptance criteria is specified in terms of depth dose variance for 10 × 10 cm field size. The ion chamber should have a small internal diameter (< 3 mm). This should not differ more than 2 % at any pair of points located symmetrically with respect to the central ray. Textbook of Radiological Safety and exposed again by blocking region 1. instead of absolute values of depth dose. It is advisable to compare depth dose ratios for depths beyond dose maximum. The tolerance limit is ± 3 %. Field Symmetry The profile generated with the above procedure can be used for checking the field symmetry. The measured depth dose data is to be used for clinical dose calculations. Time taken to drive the source to ON/OFF position and integrity of applicators are also very important. QA FOR HDR BRACHYTHERAPY Electrical and Mechanical Tests After the installation of the HDR unit. (ii) guide tube and applicator and (iii) drive cable and source etc. The acceptance limit for the probable energy is ± 0. R90. The mechanical tests included are functioning of sensors like pressure. The variation of dose relative to the dose at central axis should not exceed ± 5 % over an area confined within lines 2 cm inside the geometric edge of the fields equal to or larger than 10 × 10 cm. field size indicator (± 2 mm). gantry and collimator angles (1degree). monthly and annual QA to be carried out in a linear accelerator (Table 6. It should not be more than 2 % any pair of points located symmetrically on opposite sides of the central axis. Source safe display and treatment ON/OFF indicator are also be tested. In the electrical tests. the electrical and mechanical tests should be carried out. For range determination one can use ion chambers.5 MeV of the nominal energy. Control console display and control console functions should also be tested for electrical safety. diodes or film and RP is found from the depth dose curves. film dosimetry can be used to find R100. it is desirable to check the wedge angle (± 2 degree). isocenter shift with couch up and down motion (± 2 mm). In addition. the interlocks in the treatment room doors.6). Quality Assurance point where the tangent to the descending linear portion of the curve intersects the extrapolated background. Flatness and Symmetry The flatness of the electron beam is specified in a reference plane perpendicular to the central axis. and R50. Other Checks In addition to the above. optical distance indicator (± 2 mm). torque. emergency stop button to interrupt the irradiation are to be tested. The AAPM-TG 40 has recommended the daily. applicator and guide tubes. optical and coupling between (i) guide tube and unit. 159 . laser lights alignment with isocenter (± 2 mm) and table top sag with lateral and longitudinal travel under distributed weight (2 mm) etc. at the depth of the 95% isodose beyond the depth of dose maximum (AAPM-TG 20). R80. guide tube and treatment unit. Beam symmetry compares a dose profile on one side of the central axis to that of other side. Positional Accuracy Applicator Integrity The positional accuracy is tested by combining auto radiography and radiography. couch axis with isocenter. Coincidence of collimator.3 s or less at each dwell position. Field size indicators. Then the applicator is connected to the HDR unit in channel 3. Audiovisual monitor Light and radiation field Electron out put vs gantry coincidence. Jaw symmetry. Table top sag. Latching of wedges and tray Vertical travel of table. Distance indicator Electron beam flatness Monitor chamber linearity. the 160 remaining part of the film was shielded with lead partition. When the film exposed. Gantry rotation isocenter. This is repeated for various other applicators. 1400 and 1350 (50 mm gap). Autoradiography was performed in HDR for a period of 0. Couch rotation isocenter. Later the whole test package is taken to X-ray machine and again exposed. Gantry and collimator Off axis factor constancy angle indicators. Safety interlocks. Textbook of Radiological Safety Table 6. and symmetry.10A). A graph sheet is pasted on the therapy verification film. Electron out put Electron PDD Out put factor constancy for electron applicators. A small lead wire is kept at the end of the tandem in a transverse direction (Fig. angle. Using the graph sheet the tip of the applicator must be maintained in the same level as before. Now the applicator is moved laterally and fixed in a different position in the film. and symmetry. wedge and electron cone). Programs are made to create dwell positions at 1500. Cross hair centering. Wedge and tray position.6: QA for Linear accelerators Daily Monthly Annual X-ray out put X-ray PDD Field size dependence of X-ray output. Over the graph sheet the tandem of the standard gynaec applicator (IU3) is fixed. vs gantry angle. 6. Door interlock Safety interlocks X-ray out put vs gantry (emergency switch. Collimator rotation isocenter. 1450. The film is exposed with suitable factors with a X-ray machine. Field light intensity. . Applicator position. angle. Couch position indicators. Arc mode. This will confirm the mechanical integrity of the applicator. gantry. Localizing lasers X-ray beam flatness Off axis factor constancy. the correct Fig. 1460. 1440. 6. The film was developed and checked for the positioning accuracy and Uniformity. Quality Assurance Pin Prick Method A graph sheet is pasted on a therapy verification film. The distance between the applicator and the pin prick is 50 mm on both sides.10B: Staggered autoradiography (For color version see plate 2) . The gynec tandem or a flexible implant tube pasted on the graph sheet.10A: Radiography and autoradiography (For color version see plate 1) 161 Fig. 1420 and 1400 mm parallel to the applicator. A pin is used to mark several cardinal treatment lengths. Staggered Autoradiography Staggered autoradiography is used to confirm the correct delivery of each unique sequence of dwell positions to the programmed channel. 6. The criteria for positional accuracy is ± 1 mm. 1480. The applicator is connected to the transfer tube and the HDR source is used to expose the film. 1500. and the accurate relative positioning of the most dwell position. Similarly. The dwell time for each dwell is selected optimally to create a optical density of around one. The first position in each catheter was offset from the previous one by 2. with dwell spacing of 15 mm. Temporal Accuracy Verification of temporal accuracy consists of identically measuring the length of time the HDR source remains at the specific dwell position and comparing it with the set time. Five sets of readings are taken and the average of five sets of reading (Qave) is found and the corrected current ( Icor = Qave/T) is calculated Reading Charge 1 Charge 2 Charge 3 Charge 4 Charge 5 Change nC nC nC nC nC (Qave) nC R1 Now the system is programmed for 60 sec (Tset) and the charge for 60 seconds is noted by operating the machine timer. timer linearity and end error were determined.meas and 300 Sec and the readings are tabulated as follows: . consisting of 8 dwell positions. In the same way. 180 Sec. Textbook of Radiological Safety spacing of adjacent dwell positions. At 30 Seconds an interruption is made and the system is restarted again.Five sets of reading are taken as follows and the average R1 and R2 were found.nC R1 R2 Timer Error = (R2-R1) t /(2R1-R2) Timer Linearity The HDR system is programmed for about 320 Seconds at distance 1385 position 21 and the charge for 300 Seconds (T) is noted using an independent timer. In this study the timer error. Then the value of the Tmeas is calculated using the formula T =Qave/Icor. all the 18 channels has to be tested (Fig. The accumulated charge taking the additional transit time into consideration is noted as R2. Five sets of reading are taken and the average is found.5 mm. the readings were taken for 120 162 Sec.10B). resulting in a pattern of descending dots in which errors are readily discernible. Timer Error The HDR system is programed for 60 seconds in 1385 position 21 and the charge for 60 Seconds is noted as R1. 240 Sec. Autoradiography is performed for 1-6 channels. Again the system is programed for 60 seconds and the machine is made ON. 6. Reading Charge 1 Charge 2 Charge 3 Charge 4 Charge 5 Change nC nC nC nC nC Average. Trial treatment is performed with the Ir-192 Source for about 5 times. Average Tmeas = sec nC nC nC nC nC charge Qave/Icor (Qave)nC 60 120 180 240 300 A graph has been plotted with Tset in X-axis and Tmeas in Y-axis. Alternatively. The flexible implant tube is now cut longitudinally and the wipe test is performed using gauze. nA (ii) Now the machine set for the dwell position of Dwellmax and the measurements are repeated for 3 times. The gauze is tested for contamination using a contamination Monitor and the reading is recorded as ———CPM. Dwell position Meter reading. Linearity Error = 1 – [Tmeas max (T1) – Tmeas min (T2)] × 100 % Tset corresponds to T1-Tset corresponding to T2 End error is the intercept at Y-axis. The readings are tabulated as given 163 . The dwell position (Dwellmax) corresponding to the maximum response is found. Source Strength Verification The HDR system is to be calibrated with re-entrant type ion chamber (well chamber). Charge 5. From the graph the slope is found using the most deviated readings on both sides. the intercept can also be calculated by using Excel Sheet. Quality Assurance Tset. As a first step the axial response of the chamber is obtained. A plot is made between dwell position and relative meter readings. Charge1. Repeated readings are taken for at least 2 times for a given dwell position and tabulated as shown below. Charge 2 Charge 3 Charge 4. nA (i) Meter reading. by programing all dwell positions (say1-48). Leakage and Contamination The HDR machine is connected with a flexible implant tube and made ready for dummy treatment. The secondary standard dosimeter is used to measure the current in nA. Textbook of Radiological Safety below and the average of the readings is also found. A printout is obtained and its dimensions are compared with input data.11). making sure that the stop collar on the dummies abuts the coupler on each catheter (Fig. Periodic QA schedule Four flexible catheters are taped on a sheet and placed on the ready pack film at 2 cm apart. The isodose print out is made and checked. Average Meter nA (i) nA (ii) nA (iii) reading . At each catheter. and (iv) computational algorithm etc. A single pellet is programmed in a gynaec application. Meter reading. so that it can deliver a dose of 10 Gy at 10 mm distance. Dwell position Meter reading. The tolerance limit for data transfer is ± 1 mm. After radiographing the dummies. the HDR machine is 164 programmed to dwell 0. The temperature (T) and pressure (P) parameters are also noted. dwell . Dummies were inserted in each catheter. Similarly input is made through keyboard and the hard copy is compared. This can be repeated for different catheter lengths and orientation with marking points. (iii) dose calculation at selected anatomical points.1 sec at each dwell position.15 + T)/(273.nA (M) Dwellmax Activity = M × N × Ktp where Ktp is the temperature and pressure correction factor = ((273. Meter reading. The tolerance limits is ± 3 % for dose. A 5 cm. (ii) data transfer from orthogonal radiographs. After installation the TPS is tested for its accuracy of (i) digitization of coordinates. 10 cm and 12 cm catheter length is drawn in a graph sheet and its AP and lateral images are fed into the system through the digitizer. 6. The treatment time can be verified by either by (i) Mante carlo data or (ii) Meisberger polynomial.15 + 22)) * 1013/P) and N is the Chamber calibration factor = ( ) GBq/nA The % of variation of the measured activity with that of the stated activity (ventors) is calculated as follows: Stated activity Measured activity % variation = ×100 Stated activity QA for Treatment Planning System Quality assurance of treatment planning system (TPS) is an essential and indispensable part before commissioning any TPS. 2006. Faiz M.21:581-618. Edited by GS Pant. Delhi. 165 . 5. 25. Quality Assurance Fig. 9. Jeffrey W. 21. Med phys 1995. 3. 2003. 41. the HDR machine is again programmed as follows: Catheter 1 Dwell 5 Length 1490 Catheter 2 Dwell 5 Length 1450 Catheter 3 Dwell 5 Length 1400 Catheter 4 Dwell 5 Length 1390 After HDR autoradiography. 4.22(6):809-19. July 13-16. Himalaya publishing house. BIBLIOGRAPHY 1. Zuoferg Li. Comprehence QA for radiation oncology: Report of AAPM radiation therapy Task Group 40. the film is developed and the maximum deviation from the dummy position is checked and the tolerance is 2 mm. (3rd edn.11: Periodic quality assurance test (For color version see plate 2) positions are 1. 17. 13. 29. 48.) Lippincott Williams & Wilkins. Advances in Diagnostic Medical physics Proceedings of the international symposium on advances in diagnostic Medical physics and workshop on Cyclotron PET/CT. 33. 6. Mate carlo dosimetry of the Microselectron pulsed and high dose rate Ir-192 sources. 37. After the exposure.Khan: The Physics of radiation therapy. Med Phys1994. 45. 2. Textbook of Radiological Safety 5. in carcinoma of the uterine cexvix-PhD thesis. Biggs PJ. 166 .al. No 3. QA Instructions to users: Nucletron India. Nath R. Thayalan K. Bova FJ. 45. AAPM code of practice for radiotherapy accelerators: report of AAPM radiation therapy Task Group No. IAEA. Mylapore. Vienna 2006. Med Phys 1994. 6. European Journal of Nuclear Medicine and Molecular Imaging Vol. The Tamilnadu Dr MGR Medical university. 6.D’silva road. 31. Performance evaluation of the new whole-body PET/CT scanner: Discovery ST: Valentino Bettinardi et. et al.Chennai- 600 004. Chennai 2003. Nuclear Medicine resources book. Physical and dosimetric studies of High dose rate Brachytherapy system with clinical correlation. 9. No.867-81. 2004.21:1093-1121. 8. 7. AERB Safety code SC/MED-1. AERB Safety code SC/TR-1. Radiation Protection Rules 1971 (RPR-1971) provides necessary regulatory infrastructure for effective implementation of radiation protection program. Atomic Energy Regulatory Board. 2001 10. Chapter 7 Regulations and Dose Limits ATOMIC ENERGY ACT-1962 The primary legislation to regulate the use of ionizing radiation. Transport of radioactive material. The Act emphasizes safety while working with radiation. Brachytherapy sources. Radiation Surveillance procedures for medical applications-1989 6. was constituted on November 15. It offers special provisions to safety. Telegamma therapy equipment and installation. 1983. Medical diagnostic X-ray equipment and installations. by the President of India by exercising the powers conferred by section 27 of the Atomic Energy Act 1962 (33 of 1962). The legislation and various rules related to radiation protection in medicine are listed below.1962. AERB Safety code SC/MED-3. viz. AERB Safety code SC/MED-4(rev. Nuclear medicine facilities. in India is the Atomic Energy Act. sale and transport of radioactive materials and cognizance of offences. 2004.1). 1988 9. 1983 3. It deals with control over possession. Atomic Energy Act 1962 (33 of 1962) 2. 1986 7. Most of them are available in the form of codes and guides: 1. The Act envisage control over premises where radioactive substances are handled or radiation generating equipments are operated. It is an . Safe disposal of Radioactive Waste Rules. 2001 8. Atomic energy (Radiation protection) Rule 2004 4. under section 17 and powers to make rules under section 30 of the Act. The RPR-1971 was revised in 2004 and named as Atomic Energy (Radiation Protection) Rules. The Act empowers the Government of India to exercise control over protection and the use of Atomic energy. 1987 5. ATOMIC ENERGY REGULATORY BOARD The Atomic Energy Regulatory Board (AERB). use. AERB Safety code SC/MED-2. equipment and installation. The Act and the secondary legislation. namely:- Rule 1. The AERB is entrusted with the responsibility of developing and implementing appropriate regulatory measures aimed at ensuring radiation safety in applications involving ionizing radiations. The board is fully empowered to lay down standards and frame rules and regulations. and in supercession of Radiation Protection Rules 1971 except as respects things done or omitted to be done before such supercession. These rules may be called the Atomic Energy (Radiation Protection) Rules.S. design. . AERB has jurisdiction over all the units of the department of Atomic energy and all radiation installations in the country. These rules shall apply to practices adopted and interventions applied 168 with respect to radiation sources. 2. Short Title. RADIATION PROTECTION RULES-2004 [Published in the Gazette of India: September 11. construction. The board covers the safety aspects of all areas of nuclear fuel cycle and use of radiation in medicine. maintenance. and Sections 16. The chairman AERB is the competent authority. 17 and other relevant Sections of the Atomic Energy Act (33 of 1962) and all other powers enabling it in this behalf. 2004 G. industry and research and transport of radioactive materials.— In exercise of the powers conferred by Section 30 read with section 3 and clause (i) and sub-clauses (c) and (d) of clause (ii) of Sub- Section (1). recognized by the Government for enforcing provisions of radiation safety in the use of ionizing radiation. The board is assisted by Health. Extent and Commencement 1. and decommissioning and disposal of radioactive sources.R. commissioning. 2004. Sub-section (4) of Section 14. manufacture. the 25th August. 303. advisory committees and task groups. The mission of the board is to ensure that the use of ionizing radiation and nuclear energy does not cause undue risk to health and environment. operation. The major objectives of AERB is to develop and publicize specific codes and guides. 2004] Part-II-Section 3-Sub-section (I) Government of India Department of Atomic Energy Mumbai. which will deal with the radiation safety aspects of various applications of radiations. Textbook of Radiological Safety apex body that regulates the use of ionizing radiation in the country. the Central Government hereby makes the following rules. agriculture. It will also issue authorization related to site. Radiological physics and advisory division (RPAD). safety and environment group of BARC viz. ix. from time to time. commissioning and operation. or operate any radiation generating equipment except in accordance with the terms and conditions of a license. without a licence (a) establish a radiation installation for siting. vii. Deep X-ray units. ii. They shall come into force from the date of their final publication in the Official Gazette. No person shall. Rule 2. 3. iii. Brachytherapy. Neutron generators. and (b) decommission a radiation installation. Such other source or practice as may be notified by the competent authority. consent from AERB). Industrial radiography. Nuclear fuel cycle facilities. Any institution desire to start a radiation facility has to obtain License. Gamma irradiation chambers. Interventional radiological X-ray unit. viii. Licence 1. Telegamma and accelerators used in radiotherapy. from time to time. iv. (ii) radiation therapy equipments. 169 . irradiation chambers. authorization. No person shall handle any radioactive material. ii. and (iii) nuclear medicine equipments. Facilities engaged in the commercial production of radioactive material or radiation generating equipment. Such other source or practice as may be notified by the competent authority. (Radiation installation in medicine includes the (i) the medical X-ray equipments. v. an authorization shall be necessary. Land based high intensity gamma irradiators other than gamma. A license shall be issued for sources and practices associated with the operation of - i. 2. vi. superficial and contact therapy X-ray units. iv. and vi. Rule 3. design. Definitions Define the various terms and terminology used in the Atomic energy Act and ARPR 2004. Nuclear medicine facilities. Provided that for sources and practices associated with the operation of- i. Regulations and Dose Limits 3. registration. v. and x. Particle accelerators used for research and industrial applications. They extend to the whole of India. iii. Facilities engaged in the commercial production of nucleonic gauges and consumer products containing radioactive material. Computed tomography (CT) unit. construction. 4. Provided further that for sources and practices associated with the operation of - ii. The license shall not be transferable without the prior approval of the competent authority. Exemption The use and disposal of an substance and materials which spontaneously emit radiation not exceeding the level of radiation prescribed by notification issued under clause (i) of Sub-section (1) of Section 2 of the Act and the use of radiation generating equipment. Rule 6. RIA laboratories. Biomedical research using radioactive material. vi. Approval for package design for transport of radioactive material. design. vii. ii. Analytical x-ray equipment used for research. Rule 4. 4. from time to time. for the purposes of manufacture and supply. and vi. Such other source or practice as may be notified by the competent authority. and viii. are exempted from the purview of rule 3. Nucleonic gauges. iv. v. Approval for siting. iv. Rule 5. cosmic radiation at the earth surface. unmodified 170 concentrations of radionuclides in raw materials and from other sources . Approval for sealed sources. Approval for shipment approval for radioactive consignments. construction. iii. Such other source or practice as may be notified by the competent authority. Medical diagnostic X-ray equipment including therapy simulator. Radioactive sources in tracer studies. from time to time. Provided also that for - i. devices or appliances emitting radiation not exceeding the limit determined by the Central Government under clause (g) of Section 3 of the Act. Exclusion Exposures resulting from naturally occurring radionuclides present in the human body. appropriate fees payable for issuance of license specified in these rules. Fees for License The competent authority may prescribe by notification in the Official Gazette. a registration shall be necessary. consent shall be necessary. v. radiation generating equipment and equipment containing radioactive sources. Textbook of Radiological Safety i. commissioning and decommissioning of a radiation installation. commissioning and decommissioning. in the opinion of the competent authority - a. Regulations and Dose Limits and practices which may be prescribed as not amenable for control. No type approval of sealed sources. facilities and handling procedures afford adequate protection during normal or intended operations. or to operate radiation generating equipment.Appropriate radiation monitors and dosimetry devices are available with the applicant for purposes of radiation surveillance. All the requirements relating to safety specified by the competent authority in the relevant safety codes and safety standards have been satisfied in the construction of the radiation installation. The application for such license is for purposes envisaged by the Act. iii. Rule 7. iv. in the opinion of the competent authority. ii. 2. the applicant has demonstrated compliance with the relevant safety codes and safety standards specified by him. are excluded from these rules. by the competent authority may be issued unless. the equipment. Workers have appropriate training and instructions in radiation safety. minimize occurrence of potential exposures and enable appropriate remedial actions to be taken in the event of an accident. in addition to the appropriate qualification and training required for performing their intended tasks. 3. 171 . d. construction. In respect of approval for siting. Documentation relevant to the license and complete in all respects is submitted to the competent authority. Conditions Precedent to the Issuance of a License 1. shall be issued to a person unless. design. and e. b. No license to handle radioactive material. facilities and handling procedures afford adequate protection during normal operations. i. The applicant has demonstrated compliance with the provisions of the relevant safety codes and safety standards specified by the competent authority. c.A Radiological Safety Officer is designated in accordance with rule 19. the proposed equipment. v. An application for license shall be made to the competent authority by an employer or a person duly authorized by him. radiation generating equipment and equipment containing a radioactive source for the purpose of manufacture and supply or package design approval for transport of radioactive material or shipment approval for radioactive consignment or any other approval as notified under third proviso to rule 3. of a radiation installation. In respect of license for operation of a radiation installation. Rule 11. a. Suspension. In any location except as specified in the license. inhalation or percutaneous intake by. Rule 9. Suspend the operation of the license for a specified period of time. 2. or b. . Modification of Radiation Installation or Change in Working Condition No modification to an existing radiation installation or no change in working conditions therein. or application to. Period of Validity of License Every license issued under rule 3 shall. Considers it to be necessary in public interest pertaining to radiation safety. Activation of the aforesaid products shall not be permitted. Restriction on Certain Practices 1. a human being and sale. or ii. unless otherwise specified. Textbook of Radiological Safety Rule 8. The licensee shall ensure that individuals other than those who may be specified in the license do not handle the source. after giving a show cause notice to the licensee and also giving him an opportunity to make a representation within a period of thirty days from the date of receipt of the notice by him against the action proposed to be taken and on consideration of his representation. Restrictions on Use of Sources 1. If in its opinion. import or export of such products shall not be permitted. Practices such as deliberate addition of radioactive substances in foodstuffs. 172 2. affecting safety shall be done without the prior approval of the competent authority. beverages. Rule 13. Revoke or modify the terms and conditions of the license. Issuance of License The license shall be issued within a period of one hundred and eighty days from the date of receipt of the application subject to the condition that all the requirements for issuance of the license have been duly fulfilled. be valid for a period of 5 years from the date of issue of such license. Rule 10. and c. and cosmetics or any other commodity or product intended for ingestion. Other than those specified in the license. Rule 12. the licensee has contravened any of the provisions of these rules. b. For any purpose other than those specified in the license. Modification or Withdrawal of a License The competent authority may - i. toys. The licensee shall not handle any source:- a. personal ornaments. Safety Standards and Safety Codes The competent authority may issue safety codes and safety standards. and c. 2. On externally visible surfaces of radiation equipment. Rule 17. Rule 16. who are likely to receive an effective dose in excess of three tenths of the average annual dose limits notified by the competent authority and shall forthwith inform those employees that they have been so designated. Radiation Symbol or Warning Sign 1. radiation generating equipment and equipment containing radioactive sources. Prohibition of Employment of Persons below Certain Age 1. Dose Limits and Other Regulatory Constraints The licensee shall ensure compliance with the dose limits and other regulatory constraints specified by the competent authority by order under these rules. 2. At the entrance of controlled area and supervised area. sealed sources. The specification of the radiation symbol or warning sign shall be as prescribed by the competent authority. Rule 15. No person under the age of 18 years shall be employed as a worker. Radiological Safety Officer Every employer shall designate. with the written approval of the competent authority. Rule 19. 173 . and containers for storage of radioactive materials. from time to time. a person having appropriate qualifications as Radiological Safety Officer. Rule 18. prescribing the requirements for radiation installation. by order for that purpose. 3. Regulations and Dose Limits Rule 14. b. those of his employees. The radiation symbol shall not be used for any purpose other than those mentioned in these rules. Classified Worker The employer shall designate as classified workers. No person under the age of 16 years shall be taken as trainee or employed as an apprentice for radiation work. and transport of radioactive material and the licensee shall ensure compliance with the same. The radiation symbol or warning sign shall be conspicuously and prominently displayed at all times - a. At the entrance to the room housing the radiation generating equipment. packages for radioactive materials and vehicles carrying such packages. monitoring and assessment of exposure for ensuring adequate protection of workers. Maintain records of workers as specified under rule 24. The licensee shall comply with the surveillance procedures. 3. Provide facilities and equipment to the licensee. and g. Arrange for health surveillance of workers as specified under rule 25. The employer shall be the custodian of radiation sources in his possession and shall ensure physical security of the sources at all times. the licensee shall a. wherever applicable. 2. . The responsibility for implementing the terms and conditions of the license shall rest with the licensee. Furnish to each worker dose records and health surveillance reports of the worker in his employment annually. The employer shall inform the competent authority. Prior to employment of a worker. as and when requested by the worker and at the termination of his service. 5. d. Ensure that provisions of these rules are implemented by the licensee. Upon termination of service of worker provide to his new employer on request his dose records and health surveillance reports. 3. where applicable. 2. investigate any case of exposure in excess of regulatory constraints received by 174 individual workers and maintain records of such investigations. Every employer shall: a. Responsibilities of the Licensee 1. f. Radiological Safety Officer and other worker(s). Not allow workers. within 24 hours. Every licensee shall establish written procedures and plans for controlling. Radiological Safety Officer and other worker(s) to carry out their functions effectively in conformity with the regulatory constraints. Textbook of Radiological Safety Rule 20. procure from his former employer. Arrange for preventive and remedial maintenance of radiation protection equipment. b. b. c. c. Rule 21. members of the public and the environment and patients. The licensee shall comply with the provision of rules for safe disposal of radioactive waste issued under the Act. Without prejudice to the generality of the above. Inform the competent authority if the licensee or the Radiological Safety Officer or any worker leaves the employment. other than those specified in sub-clause (ii) of clause (e) of sub-rule (2) of rule 7 and already dealt with under rule 17. In consultation with the Radiological Safety Officer. d. safety codes and safety standards specified by the competent authority. e. and monitoring instruments. the dose records and health surveillance reports. of any accident involving a source or loss of source of which he is the custodian. 4. Responsibilities of the Employer 1. Investigate any situation that could lead to potential exposures. h. Inform the competent authority when he leaves the employment. j. n. Conduct or arrange for quality assurance tests of structures. k. g. Advise the employer regarding - i.Advise the employer about the modifications in working condition of a pregnant worker. 175 . Verify the performance of radiation monitoring systems. b. investigation and follow-up actions in cases of exposure in excess of regulatory constraints. The Radiological Safety Officer shall be responsible for advising and assisting the employer and licensee on safety aspects aimed at ensuring that the provisions of these rules are complied with. The safe storage and movement of radioactive material within the radiation installation. Regulations and Dose Limits e. Carry out physical verification of radioactive material periodically and maintain inventory. including steps to prevent recurrence of such incidents. The licensee shall ensure that the workers are familiarised with contents of the relevant surveillance procedures. l. Inform competent authority promptly of the occurrence. safety interlocks. prepare emergency plans. c. safety standards. 2. Responsibilities of the Radiological Safety Officer 1. f. The Radiological Safety Officer shall:- a. safety aides and safety manuals issued by the competent authority and emergency response plans. The necessary steps aimed at ensuring that the regulatory constraints and the terms and conditions of the license are adhered to. ii. Rule 22. Carry out routine measurements and analysis on radiation and radioactivity levels in the controlled area. m. for responding to accident to mitigate their consequences and ensure emergency preparedness measures. i. Inform the employer and the competent authority of any loss of source. Inform the competent authority if the Radiological Safety Officer or a worker leaves the employment. In consultation with Radiological Safety Officer. components and sources and related equipment. 6. supervised area of the radiation installation and maintain records of the results thereof. Inform appropriate law enforcement agency in the locality of any loss of source. and o. safety codes. systems. Investigate and inform the competent authority of any accident involving source and maintain record of investigations. as specified in rule 33. protective devices and any other safety systems in the radiation installation. b. Routine measurements and analysis on radiation and radioactivity levels in the off-site environment of the radiation installation and maintenance of the results thereof. radiation monitors and Personnel monitoring devices as provided. Furnish to the licensee and the competent authority the periodic reports on safety status of the radiation installation. licensee and Radiological Safety Officer in order that her working conditions may be modified. e. Developing suitable emergency response plans to deal with accidents and maintaining emergency preparedness. notify the employer. if necessary. and c. Monitoring instruments are calibrated periodically. Assist the employer in - i. The safety and security of radioactive sources. Every worker shall observe the safety requirements and follow safety procedures and instructions and shall refrain from any wilful act that could be detrimental to self. and h. ii. of any accident or potentially hazardous situation that may come to his notice. The safe disposal of radioactive wastes. Ensure that - i. Quality assurance tests of structures. Inform the licensee and the Radiological Safety Officer. if any. Provide to the employer information about his previous occupations including radiation work. components and sources. Make proper use of such protective equipment. The worker shall:- a. The modifications in working condition of a pregnant worker. systems. Reports on all hazardous situations along with details of any immediate remedial actions taken are made available to the employer and licensee for reporting to the competent authority and a copy endorsed to the competent authority. and iii. 3. as applicable are conducted. on becoming aware that she is pregnant. 2. Responsibilities of Worker 1. d. and ii. A female worker shall. Initiation of suitable remedial measures in respect of any situation that could lead to potential exposures. Textbook of Radiological Safety iii. Instructing the workers on hazards of radiation and on suitable safety measures and work practices aimed at optimizing exposures to radiation sources. 176 . and ii. g. Rule 23. co-workers. and iii. Inform the competent authority when he leaves the employment. f. Advise the licensee on - i. and iv. the radiation installation and public. and iii. health surveillance to decide on the fitness of each worker for the intended task. A worker shall have access to his personnel monitoring and the health surveillance records. The exposure of humans for biomedical research is carried out only on healthy volunteers with their prior consent in writing. Every employer shall provide the services of a physician with appropriate qualifications to undertake occupational health surveillance of classified workers. the health surveillance specified in rule 25. shall for optimizing the medical exposure ensure that - a. and b. thereafter at least once in three years as long as the individual is employed. 177 . 2. Performance of the equipment is verified periodically by appropriate quality assurance tests. Every licensee shall maintain complete and up-to-date records of - a. and classified worker. c. The health surveillance shall include - a. personnel monitoring under Clause (b) of sub-rule (2) of rule 27. shall be subjected to the following - a. Health Surveillance of Workers 1. for workers who have received dose in excess of regulatory constraints. initially on employment. Every worker. general medical examination as specified by order by the competent authority. b. Rule 26. and b. activity administered to patients for diagnostic and therapeutic purposes. in the format as specified by order by the competent authority. or not less than 30 years after the termination of the work involving occupational exposure whichever is later. and afterwards until the worker attains or would have attained the age of 75 years. 2. counseling of pregnant workers. sealed or unsealed sources. Medical Exposures The licensee carrying out diagnostic or therapeutic work using radiation generating equipment. Rule 25. Such records shall be preserved during the working life of each worker. special tests or medical examinations as specified by order by the competent authority. Records are maintained for a period specified by the competent authority of - i. The methodology. 3. Regulations and Dose Limits Rule 24. and b. radiation doses received by therapy patients.other relevant parameters. 3. ii. Records of Workers 1. transport of radioactive material in public domain shall be in accordance with the procedures laid down by the competent authority and in accordance with the other regulations pertaining to transport by different modes. without prejudice to other course of action available. Rule 27. from time to time. the competent authority may. appropriate quality assurance requirements in the above. When. any worker has exceeded the dose constraints. c. if any. and d. issue appropriate directives for controlling further exposure and the employer shall comply with the directives. commissioning. b. in the opinion of the competent authority. Power to Appoint or Recognize Persons or Agencies The competent authority may. c. Any accidental medical exposure is investigated and a written report is submitted to the competent authority. Radiation Surveillance Requirements 1. servicing and maintenance and decommissioning of facilities involving the use of radiation. 2. Rule 29. that the competent authority may impose in this regard. such radiation surveillance requirements and procedures may provide that - a. Directives in the Cases of Exposures in Excess of Regulatory Constraints a. and disposal of radioactive material shall be done in accordance with the specifications laid down by the competent authority in the relevant safety codes and safety standards. the siting. The competent authority may by order specify appropriate radiation surveillance requirements and procedures and the employer and the licensee shall comply with them. the workers shall be subjected to personnel monitoring and health surveillance and appropriate records shall be maintained. Textbook of Radiological Safety the number of volunteers and the radiation dose they are subjected to shall be reviewed by the ethical review committee constituted by the employer. the employer shall assign alternative work not involving exposure to radiation. Without prejudice to the generality of the foregoing provisions. and d. until the competent authority is satisfied about the fitness of the worker to resume radiation work. construction. If a worker discontinues radiation work under the directives of the competent authority issued under this rule. The employer shall comply with restrictions. Rule 28. operation. design. b. prescribed in . appoint or recognize 178 persons or agencies having the qualifications and expertise. The findings of the inspection shall be forwarded to the licensee for necessary corrective actions. Inspection of Premises. b. The person authorised to conduct inspection may – a. 5. 2. Review and verify whether the corrective actions have been implemented. construction. Make such tests and measurements as may be necessary for the purpose of assessing radiation safety. for the purposes of enforcement of these rules. Rule 30. c. Regulations and Dose Limits the relevant safety code. if any. checking that respective operating personnel are competent to operate the facility. 6. That the facilities are operating as per the approved technical specification. or radiation installation. Investigate unusual incidents or accidents. 179 . Any person duly authorized under Sub-section (4) of Section 17 of the Act may. inspect any premises. 3. The employer and the licensee shall extend all assistance to enable the inspection to be carried out effectively and unhindered. for the purpose of performing any of the functions entrusted to them by the authority and for ensuring compliance with radiological surveillance. Inspect radioactive consignments in any conveyance carrying radioactive material and inspect any package containing radioactive material. commissioning. whether the safety related structures. that had occurred at the radiation installation and arrive at the reasons for the same and recommend corrective measures. ii. or conveyance. Inspect. Conducting all such examinations (including verification of relevant records) as may be considered necessary. Radiation Installations and Conveyances 1. and iii. from safety point of view. d. systems. siting. The date and time of inspection may or may not be informed to the employer or the licensee prior to the inspection. and e. Inspection may be carried out at all licensing stages. to ensure that the licensee has fulfilled the radiological safety requirements for carrying out the practices at the radiation installation as per the stipulations laid down in the licence. 4. This shall include - i. Checking. on the relevant safety codes and safety standards specified by the competent authority and that they are functioning as per the design intent. components and devices are of approved quality based. operation and decommissioning. namely. Emergency Preparedness 1. The licensee shall submit the response plans for plant emergencies and site emergencies to the competent authority for approval. Seal or Seize Radiation Installation or Radioactive Material and to give Direction to the Employer 1. Intervene and issue such directions as deemed fit and proper under the circumstances in the interest of radiation safety and the employer shall act as per the directions of the competent authority and shall make every effort to mitigate the consequences of the accident. The competent authority may assign experts to give advice or render assistance in mitigating the consequences of the accident and the expenses incurred. carry out investigation for the purposes of determining contravention of any of the provisions of these rules. Rule 32. and b. 2. Power to Investigate. or b. The licensee shall prepare emergency response plans as specified by the competent authority in the relevant safety codes and maintain emergency preparedness. In respect of radiation installations governed by clause (a) of sub-rule 180 (3) of rule 3 and clause (b) of sub-rule (3) of rule 3. emergency response . 4. Any person duly authorised under Section 17 of the Act. workers. may. the competent authority may issue such directions as it may deem fit for ensuring safety including the immediate shutting down of the radiation installation and the employer shall comply with the directions. if any. Rule 33. shall be reimbursed by the employer. In the interest of safety of the radiation installation. The licensee shall submit the response plans for off-site emergencies prepared by the appropriate authorities to the competent authority for review. 3. Directives in Case of Accidents 1. 3. Textbook of Radiological Safety Rule 31. The investigation may be carried out against a complaint or on suspicion or after an unusual incident or accident. 2. the competent authority may - a. Indicate in writing to the employer any recommendation aimed at ensuring adequate protection and the licensee shall comply with the same. Seal any radiation installation or any conveyance carrying radioactive materials or seize any radioactive material or contaminated equipment. 2. public and the environment. In the event of an accident involving the source or release of radioactive material. The person authorised to investigate may - a. after inspection. REGULATORY CONTROLS FOR DIAGNOSTIC X-RAY EQUIPMENT AND INSTALLATIONS 1. Offences and Penalties Any person who contravenes the provisions of these rules or any of the terms and conditions of license issued hereunder. – [F.V. AEA/30(1)/2002-ER].The manufacturer/vendor shall obtain design certification from the competent authority prior to manufacturing the X-ray equipment. 5. the importing /vending agency shall obtain a No Objection Certificate (NOC) from the competent authority. 3. the employer shall ensure its decommissioning. leasing or loan. Registration of X-ray equipment: Acquisition of an X-ray equipment. gift. The decommissioning plan shall take due cognizance of disposal of radioactive wastes. Approval of layout: No X-ray unit shall be commissioned unless the layout of the proposed X-ray installation is approved by the competent authority. shall be registered with the 181 competent authority by the person acquiring the equipment. When a radiation installation or radiation generating equipment ceases to be in use. The licensee shall comply with such directive as may be issued by the competent authority to ensure adequate protection of the persons in and around the decommissioned installation. 4. Secy. Rule 35. 2. RAJA. Rule 34. For equipment of foreign make. 3.P. recycling of materials. transfer. by purchase. Jt. Design certification: Every medical diagnostic X-ray equipment shall meet the design safety specifications stipulated in the safety code (SC/ MED/-2(Rev. and reuse of equipment and premises. . Type approval /No objection certificate: Prior to marketing the X-ray equipment the manufacturer shall obtain a Type approval certificate from the competent authority for indigenously made equipment. Decommissioning of Radiation Installation 1. 4. 2. prior to marketing the equipment. shall be punishable as provided for under the Act. Regulations and Dose Limits plans shall be submitted to the competent authority prior to the commissioning of the installations. Any modification to the emergency plan shall require prior approval of or review by the competent authority. No employer shall decommission a radiation installation without the prior approval of the competent authority. The application for approval shall be made by the person owning responsibility for the entire X-ray installation.No. Only Type approved and NOC validated equipment shall be marketed in the country.1)). Personnel Requirements Every hospital shall have a qualified RSO (either full time or part time). X-ray technologist and a service engineer. exposure charts. 6. training. Commissioning of X-ray equipment: No X-ray equipment shall be commissioned unless it is registered with the competent authority.25 and 26 of the Atomic Energy Act.1). operating manuals and a copy of safety documents issued by the competent authority from time to time. Inspection of X-ray installations: The diagnostic X-ray installations shall be made available by the employer/owner for inspection. Textbook of Radiological Safety 5. Certification of service engineers: Only persons holding valid certificate from the competent authority shall undertake servicing of X-ray equipment. The punishment may include fine. and maintenance facilities during useful life time of X-ray equipment. at all reasonable times. imprisonment.1962. Decommissioning of X-ray installations: Decommissioning of X-ray equipment shall be registered with the competent authority immediately by the employer /owner of the equipment 8. the manufacturer shall provide the required phantoms for dosimetry and image quality checks. In the case of CT scan. or both. Such certification shall be granted on the basis of adequacy of the persons qualifications. 182 . Certification shall be granted on the basis of qualifications. The minimum qualification and experience required are given the safety code AERB/SC/MED-2 (Rev. 7. He should be delegated with the responsibility of ensuring radiation safety applicable to the installation. to the competent authority or its representative. experience and testing /survey / dosimetry equipment available 9. Certification of RSO: Any person accepting assignment to discharge the duties and functions of RSO in diagnostic X-ray installations shall do so only after obtaining certification from the competent authority for the purpose. shall be punishable under sections 24. Any person who contravenes the provisions of these rules or any other terms or conditions of license/registration /certification granted to him/her by the competent authority. to ensure compliance with the safety code. Radiologist. experience and safety record of such person and availability of servicing facilities. depending on the severity of the offence. Personnel Responsibilities Manufacturer The manufacturer /vendor of the equipment shall make available to the user the procedures to QA tests. Employer The employer should ensure the availability of qualified RSO and qualified personnel for handling the X-ray equipment. its location. maintain proper records of periodic QA tests and personnel doses. address. educate and train new entrants. This includes the issuance of administrative instructions in writing. about the equipment. The RSO shall ensure that all radiation measuring and monitoring instruments in his custody are properly calibrated and maintained in good 183 . He should also ensure the availability of safety codes. Radiologist The radiologist shall undertake an X-ray examination on the basis of medical requirement. issued by the competent authority to the workers. Radiological Safety Officer (RSO) The RSO assist the employer to fulfill the regulatory requirements. public protection and operational safety in handling X-ray equipment and other associated facilities. He should also provide the required equipments and facilities to discharge their duties. X-Ray Technologist X-ray technologist and other attending staff shall ensure appropriate patient protection. to deal with radiation emergencies. the name and address of the owner and the nature of defects that make the equipment hazardous. The employer should ensure that persons handling medical X-ray equipment are duly abide by the provisions of the safety code. Regulations and Dose Limits Service Engineer The service engineer undertaking services in a radiological installation shall immediately report to the competent authority. conduct periodic radiation protection surveys. and take local measures. applicable to that installation. The employer shall also be responsible for ensuring that personnel monitoring devices are made available to the radiation workers. He/she so conduct the examination as to achieve maximum reduction in radiation dose to the patient while retaining all clinically important information. instruct all workers on relevant safety measures. He shall implement all radiation surveillance measures. Student/Trainee Medical students/trainees shall not operate X-ray equipment except under direct supervision of authorized operating personnel. He should furnish brief description of the equipment. which is no longer safe for use. 3. Nuclear medicine facilities carrying out diagnostic in-vivo/in-vitro investigations shall an RSO of level-II . The consentee shall not lend. The consentee shall maintain an up to date inventory and account for decay and disposal of sources.whereas facilities where therapy is also carried out shall have RSO of level-III. The consentee shall ensure that persons handling radioactive materials for nuclear medicine purposes are familiar with the mandatory provisions of RPR 2004. 8. The consentee shall ensure compliance with the mandatory requirements specified in the above documents. Atomic energy (safe disposal of radioactive waste) rules 1987. to function as RSO. and safety directives issued by the competent authority from time to time. Radiation surveillance procedures for Medical applications of radiation. The consentee shall be solely responsible for the safety and security of the radioactive material. 6. The nuclear medicine facility shall not be commissioned until the competent authority approves the facility. REGULATORY CONTROLS FOR NUCLEAR MEDICINE FA- CILITIES Consent 1. The consent is issued on the basis of written application. shall be maintained for future follow up. The consentee shall designate with the approval of the competent authority a person having suitable qualifications. Any change or modification to an already approved facility shall be carried out only with the prior approval/sanction of the competent authority. The consentee shall not take the radioactive material out of the approved premises. Authorization from competent authority is required to procure radioactive material. 4. Radiation surveillance procedures for transport of Radioactive material. its proper use. 5. deficiencies noticed and remedial actions taken. 184 . gift. authorization. license or exemption from regulatory control as established by the competent authority. and the safe disposal of wastes. Transport of radioactive material in public domain shall be in accordance with the provisions of code AERB/SC/TR-1. dose mappings. Textbook of Radiological Safety condition. Radioactive material shall not be disposed off without prior approval of the competent authority. 2. or sell any radioactive material and shall not receive radioactive material other than those specified in the authorization. 7. 1989. 1988. The consent for any practice involving radiation exposure is based on a system of notification. and other instructions of the competent authority in specific cases. including layout drawings. transfer. Suitable records of such surveys. registration. the radioactive sources available in house. provide appropriate equipment and tools to concerned persons for safe handling of radioactive material. The nuclear medicine facility shall be decommissioned only after prior approval of the competent authority and after all radioactive and contaminated materials from the facility. and b. He shall constitute a local safety committee to review the operational safety. He shall also provide personnel monitoring devices to the radiation workers. Indicate in writing to the consentee any modification aimed at providing adequate protection. Seal the institution or transport or conveyance carrying radioactive materials or seize radioactive material or contaminated equipment. on inspection. He should also ensure the availability of safety codes. and a RSO either Level-II or Level- III. If. Any person who contravenes the provisions of these rules or any other terms and conditions of approval granted to him/her by the competent authority. He should report the competent authority about the safety committee. the inspectors may a.1). the radioisotope inventory. records of unusual occurrences during handling of the sources and transport of radioactive materials. issued by the competent authority to the workers. 11. Personnel Requirements Every nuclear medicine department shall have a qualified nuclear medicine physician. Personnel Responsibilities Consentee The consentee shall employ adequate number of personnel. instruments and devices used for the above and / or quality assurance programme. Regulations and Dose Limits 9.25 and 26 of the Atomic Energy Act. quality assurance. imprisonment. any evidence of non compliance of any of the mandatory provision is noticed. Any person duly authorized by the competent authority may inspect the nuclear medicine facility. depending on the severity of the offence. shall be punishable under sections 24. 1962. ethical aspects and regulatory compliance. 185 . nuclear medicine technologist. The punishment may include fine. change in safety and unusual occurrence if any. The minimum qualification and experience required are given the safety code AERB/SC/MED-4 (Rev. records of area monitoring and contamination monitoring. and the consentee shall comply with the same 10. logbooks. Prior approval of the competent authority is necessary for reuse of the facility. or both. He should also assist the RSO in maintaining the records of inventory. iii. Nuclear Medicine Technologist i. management of cadavers containing radionuclides. He shall carry out radiation and contamination monitoring of work areas. After administration of radioisotope. QA checks and maintenance ii. He should maintain records of the doses of workers. He should ensure the purity of radiopharmaceutical. He should also take precautions to avoid misadministration. Radiological Safety Officer (RSO) The RSO assist the consentee to fulfill the regulatory requirements. and maintain record of findings. Textbook of Radiological Safety Nuclear Medicine Physician i. report unusual incident in writing to the consentee and take remedial measures. Prior clearance from the nuclear medicine committee is required for any trail. The efficacy of new nuclear medicine procedures is based on the experience of previous clinical trails. animal experiments and published literature. therapy patients. and ensure safety. administered with radioactivity iii. use. to avoid radiation exposures to the family members. He should capable of managing emergency situations. route of administration and the accuracy of dosage before giving to the patient. A consent is obtained from the patient for all nuclear medicine procedures. The nurses and ancillary staff should be instructed about radiation safety and precautions to be adopted during nursing the patient. v. iv. any unusual incident. The RSO shall ensure that all radiation measuring and monitoring instruments in his custody are properly calibrated and maintained in good condition. Prevent any possibility of misadministration and promptly report to the consentee and the competent authority about misadnistration. waste disposal of sources and other safety matters. used. He should ensure proper functioning of all equipments. disposed. if admitted to the hospital. the patient should be kept under isolation. Spread of contamination and radiation exposure to others should be prevented. Spillage of radioactivity or contamination of the patient. The patient should be informed about the safety measures. carry out periodic calibration. adverse reaction or death of a patient. inventory of sources 186 received. security and containment of radioactive sources. . radioactive waste disposal sites and public areas. premises. The RSO should be informed about any mishap in dispensing / administration of dosage to the patient or any unusual incident. iv. persons and material should be avoided. patient areas. ii. cause of such incident and remedial measures taken. 2. AERB Guidelines for Starting Radioisotope Laboratory Radioisotopes in India can be procured and handled only by the users duly 187 authorized by AERB. MBq 131 I 10 400 400 90 Y (colloid) 200 2000 70 198 Au (Colliod) 400 400 100 32 P 100 2000 30 89 Sr 50 2000 20 3. The hospital staff and the persons involved in washing. water proof flooring. The following precautions shall be observed in respect of dead bodies containing quantities more than that given in the above table: i. preparing and transporting the body to the burial ground shall be instructed by RSO on dose- reducing precautions. Table 7. 4.1: Maximum activities of radionuclides for disposal of corpses without special precautions Radionuclide Postmortem / Burial. provided the collective equivalent dose received in the procedure will be less than that in handling the cadaver as it is. instrument cabinet and a washing stand for pathologist. This authorization is based on the radiological safety . Regulations and Dose Limits Management of Cadavers Containing Radionuclides 1. receptacles for organs. burial or cremation of the corpse containing the quantities less than that specified in the Table 7. MBq embalming. A refrigerator for keeping the cadavers at temperatures below -10 degree shall be provided. Burial: Relatives shall be prevented from coming into contact with the body and people must not stay near the coffin. Embalming: Embalming is undesirable and. if unavaiodable. iii. All contamination control measures shall be observed under the guidance of RSO. ii. shall be obtained from RSO. shall be done by injection method. MBq Cremation.1. Autopsy on contaminated cadavers shall be performed only in a special autopsy room provided with facilities such as a plastic covered table. The body shall be handled with disposable gloves and kept on plastic sheets to control spread of contamination. and specific precautions to be observed during cremation. No special precautions are normally necessary for embalming. Cremation: Prior authorization. The RSO shall supervise autopsy procedures and subsequent decontamination operations. All reasonable efforts should be made to remove fluids or organs in which radionuclide is concentrated. AERB Classification of Radioisotope Laboratories The Atomic Energy Regulatory Board (AERB) proposes to classify institution using unsealed radioisotope for non clinical applications in the country and to specify the activities of the radioisotopes which can normally be handled by each user institution. fume hoods. Further. The classification will depend upon the quantity of radioisotope used and the required handling facilities. TYPE-II and TYPE-III laboratories. University. 750/. will depend on the classification of the laboratories and 188 . the radioisotope laboratory has to be classified for regular procurement of handling of radioisotopes. the institution should approach AERB for commissioning the laboratory for handling radioisotopes and for issuance of authorization / NOC for procurement of radioisotopes. activity and the type of experiments to be carried out using the radioactive materials. This classification will be broadly based on the relevant recommendations of the International Commission on Radiological Protection (ICRP) and International Atomic Energy Agency (IAEA). department. The plan of the radioisotope laboratory will depend upon the type of the radioactive material used. if any. In general. its physical from. positions of the doors. Bodies) as charges towards the approval of the plan. the minimum requirement is of two rooms of suitable dimensions (adjacent to each other).(for Pvt. windows. namely TYPE-I. It should also indicate the dimensions of the rooms. Based on the above. Based on the facilities available as per Annexure-II the institution using radioisotope will be divided into three types. one for storage and handling of radioisotopes and the other for counting of radioactive samples. A site plan (drawn to scale 1:500) of building should also be sent marking clearly therein the location of radioisotope laboratory and the occupancies around it including those above the ceiling and below the floor. After approval of the plan and equipping and furnishing the laboratory as per this guideline. one should send to AERB. The institution is required to pay Rs. The maximum authorized limits of activities that can be procured routinely from Board of Radiation and Isotope Technology (BRIT).1500/.(for Govt. workbenches and other fixtures. For this purpose it is mandatory that the plan of the radioisotope laboratory is approved by AERB from radiation safety standpoint. exhausts. Textbook of Radiological Safety status of the institution intending to establish a radioisotope laboratory. two copies of the layout of the radioisotope laboratory (drawn to scale 1:50) indicating therein the rooms meant for storage and handling of radioisotopes and counting of radioactive samples. Public Sector undertaking)/Rs. Accordingly the radioisotopes have been arranged in four groups based on their radio toxicity as per Annexure-I. Regulations and Dose Limits radionuclides which can be handled at a time will also depend on whether the operations are (i) simple wet. the manipulations are simple and do not result in any significant radiation exposure to the working personnel. These procedures will help in reducing the delay in the authorization and supply of radionuclides available in India. (ii) complex wet. usually not exceeding 3. The recommended procedure for supply of radioactive material is given in the enclosed Annexure-III. These assays are useful for the clinical evaluation of the concentration levels of vitally important biological ingredients such as hormones. without clearance for individual radionuclides from AERB. the quantities ordered should be so adjusted that the overall limits are not exceeded. to a considerable extent. Normally no personnel monitoring is required for persons working in RIA laboratories. The advantage of this technique is that it does not involve administration of radioisotopes to the patient and so no radiation exposure to the patient. these authorizations are issued subject to the user satisfying the basic safety requirements and adequate trained staff. Once the laboratories are classified. Usually. The table giving activities of radionuclides of different group that can be procured and handled by each type of laboratories is also enclosed in Annexure-IV. thereby enabling early diagnosis of various diseases and better management of treatment.7 MBq of lodine-125 and Tritium (3H). However.. If two or more radionuclides from the same group or different group are ordered. AERB Guidelines to Set Up a Radioimmunoassay (RIA) Laboratory Introduction Radioimmunoassasy has been established as a versatile and unique procedure. However. Minimum Facilities Required The equipment and facilities normally available in a hospital or pathological laboratory can be readily supplemented and used for RIA work. in most cases. RIA work involves the handling and use of very small quantities of radioisotopes. this will also involve more detailed accounting of radionuclides by the user institution. Radiation Protection Rules (2004) promulgated under the Atomic Energy Act. precautions should be taken to safeguard against spread of contamination to the counting tubes and the counter itself. steroids. This can be achieved to a large extent by good work practice. Any liquid waste 189 . the supply of the radionuclides within specified limits will be effected by BRIT. vitamins. and (iv) dry and dusty. 1962 requires that the user should obtain authorization from Atomic Energy Regulatory Board (AERB) for handling radioisotopes. drugs etc. (iii) simple drying. If ready- to-use kits are employed. Procedure for Authorization As a first step the intending user should send two copies of the layout of his proposed RIA laboratory to Head. extra precautions and facilities will be required. Project House. one of the copies of the layout will be duly approved and sent back by AERB to the institution.Purav Marg. Trombay. Textbook of Radiological Safety arising from the RIA procedure can be disposed off in the sink provided in the storage area and the used RIA vials should be disposed off in such a way as to avoid reuse. If labeling with radioiodine (involving use of a few millicuries of 125I) is contemplated. One of the suggested methods is to crush them before disposal. Bombay 400 085. Deonar. Mombay 400 094. AERB will issue the requisite NOC/ authorization. BARC. In India.N. correspondence can be had with Head. REGULATORY CONTROL FOR RADIOTHERAPY EQUIPMENT AND INSTALLATIONS Teletherapy Installation 1. BARC. AERB. For further details. Bombay 400085. Radiopharmaceuticals Division. RSD. Mumbai-400 094 for approval. the intending user has to obtain a ‘No Objection Certificate’ from Head. A four weeks training course on “RIA and its Clinical Applications’ is conducted normally twice a year by the Radiopharmaceuticals Division of BARC. RIA kits are supplied by the Board of Radiation & Isotope Technology. Handling of a telegamma therapy source/equipment or Linear 190 accelerator shall be done only in accordance with the terms . Radiological safety division. V. If the information is in order and facilities found adequate. The AERB may review the layout. the user should correspond with Head. issuance of NOC / authorization and commissioning / decommissioning the RIA laboratory the user is advised to contact Head. RSD. The personnel engaged in the actual work should have adequate knowledge of the basic procedures of counting and should be aware of some simple precautions to be taken in handling of radioactivity. For matters pertaining to planning of RIA laboratory. AERB. AERB should be approached for issuance of NOC/authorization for the procurement of RIA kits. fixtures and handling equipment and the qualified staff duly appointed. When the laboratory is duly constructed and equipped with fittings. If found suitable from radiation safety point of view. Anushaktinagar. suggest modifications from radiation safety standpoint. Radiopharma- ceuticals Division. For import of kits. which should be implemented by the party and a revised plan submitted for final approval. For all information pertaining to availability and use of RIA kits supplied by BRIT. Mumbai-400 094 on the basis of the authorization issued by AERB to the user. 191 . The punishment may include fine. Teletherapy/Tele gamma therapy sources/equipment shall be used only in the premises authorized in the license. 25 and 26 of the Atomic Energy Act. Any change in the parameters necessitating augmentation of radiation shielding or modification in the approved plan shall be carried out only with the concurrence of the competent authority. Telegamma therapy sources and equipment/linear accelerator shall meet the design safety specifications stipulated in the safety code. Telegammatherapy/teletherapy equipments shall not be lent.1986. 4. 8. The teletherapy installation shall be made available by the licensee for inspection by the competent authority or its representative. 1962. 2. The transport requirement should comply the transport code AERB/SC/TR-1. He must also ensure that any other measures of safety as the competent authority may stipulate at any time in each individual case are duly implemented without any delay. 5. Compliance with the safety code is a prerequisite for the issuance of the said license. The construction of the teletherapy insatallation shall be undertaken only after obtaining prior approval from the competent authority for the room design and equipment layout from the radiation protection point of view. shall be punishable under sections 24. gifted. or both. 9. as the case may be. A type approval certificate for the sources/equipment manufactured in the country or a No Objection Certificate (NOC) for the sources/equipment imported into the country. The manufacturer/vendor must obtain design certification from the competent authority prior to marketing the Linear accelerator / tele gamma therapy equipment. Decommissioning and disposal of Linear accelerator/Tele gamma sources/equipments shall be undertaken with prior approval of the competent authority. 7. Telegamma therapy sources shall not be transported in public domain with out prior approval of the competent authority. Any person who contravenes the provisions of these rules or any other terms and conditions of approval granted to him/her by the competent authority. imprisonment. transferred. Regulations and Dose Limits and conditions of a license granted by the competent authority. Sources should not be taken out of the said premises for any purpose without the prior approval of the competent authority. 6. sold or disposed off by the licensee with out the prior approval of the competent authority. 3. 10. The employer must ensure that persons handling Teletherapy/tele gamma therapy equipment duly abide by the provisions of the safety code and their further elaboration in various guides issued by the competent authority. depending on the severity of the offence. Textbook of Radiological Safety Brachytherapy Sources. depending on the severity of the offence. gifted. as the case may be. Handling of a Brachytherapy source shall be done only in accordance with the terms and conditions of a license granted by the competent authority. 5. Equipment and Installations 1. Radioactive sources shall not be transported in public domain with out prior approval of the competent authority. transferred. Radioactive sources shall not be lent. 2. Radioactive sources shall be used only in the premises authorized in the license. Decommissioning and disposal of Brachytherapy sources/equipments shall be undertaken with prior approval of the competent authority. sold or disposed off by the licensee with out the prior approval of the competent authority. shall be punishable under sections 24. The brachytherapy installation and its sources shall be made available by the licensee for inspection by the competent authority or its representative. Any change in the parameters necessitating augmentation of radiation shielding or modification in the approved plan shall be carried out only with the concurrence of the competent authority. The transport requirement should comply the transport code AERB/SC/TR-1. Any person who contravenes the provisions of these rules or any other terms and conditions of approval granted to him/her by the competent authority. Compliance with the safety code is a prerequisite for the issuance of the said license. imprisonment. 9. The employer must ensure that persons handling teletherapy / tele gamma therapy equipment duly abide by the provisions of the safety code and their further elaboration in various guides issued by the competent authority. 4. 192 . A type approval certificate for the sources /equipment manufactured in the country or a No Objection Certificate (NOC) for the sources/ equipment imported into the country. 1962. 25 and 26 of the Atomic Energy Act. The manufacturer/vendor must obtain design certification from the competent authority prior to marketing the teletherapy / tele gamma therapy equipment. 6. Sources should not be taken out of the said premises for any purpose without the prior approval of the competent authority. 10.The punishment may include fine. or both.1986. 8. The construction of the brachytherapy installation rooms shall be undertaken only after obtaining prior approval from the competent authority for the room design and equipment layout from the radiation protection point of view. 7. are promptly implemented. Brachytherapy sources and equipment shall meet the design safety specifications stipulated in the safety code. 3. He shall also ensure that any other measures of safety as the competent authority may stipulate at any time in each individual case . Medical physicist. implement all radiation surveillance measures. Further he shall provide all necessary facilities to the RSO to discharge his duties and functions. All radiation workers should be trained by the RSO in the management of radiation emergencies. 2. However. He shall ensure due compliance with the terms and conditions of the license issued to him by the competent authority. to deal with radiation emergencies. Manufacturer: The manufacturer /vendor of the equipment shall provide to the user the procedures to QA tests. The RSO shall ensure that all radiation measuring and monitoring instruments are properly calibrated and maintained in good working condition. He shall maintain proper records of the personnel doses. In the case of Brachytherapy. License: The responsibility of ensuring radiation safety. 4. He shall control storage and movement of sources in Brachytherapy and conduct periodical surveys. the licensee or technologists leaves the institution. including clear administrative instructions in writing. the ultimate responsibility of proper treatment shall vest with the radiation therapist. 3. the vendor must provide the certified strength and out put of each of the sources along with isodose curves. The vendor shall provide the central axis depth dose and isodose curves for single fields. Technician (Radiation therapy). 193 . Radiological safety Officer (RSO) Level-III and a service engineer. availability of qualified personnel and providing them requisite facilities to discharge their duties and functions shall rest with the licensee. Radiological safety officer (RSO): The RSO shall instruct all radiation workers on relevant safety measures. 1. The minimum qualification and experience required are given the safety code AERB/SC/MED-1 and AERB/SC/MED-3. conduct periodic radiation surveys and take suitable local measures. Medical physicist and Therapy technicians shall carry out radiation therapy with due regard to patient protection and operational safety in handling the tele-gamma therapy / linear accelerator/Brachytherapy sources and equipment. It is the responsibility of the employer to inform the competent authority if the RSO. educate and train new entrants. Regulations and Dose Limits Personnel Requirements Every institution having a radiotherapy facility shall have qualified full time Radiation therapist. operating manuals and operation and maintenance details and a copy of safety documents issued by the competent authority from time to time. Personnel Responsibilities The team comprising of radiation therapist. Employer: The employer shall provide adequate number of personnel and facilities to the licensee to discharge his responsibilities effectively. specified in these documents. RCC may be used. Atomic Energy Regulatory Board. In addition a backup arrangement must be made. unless the user complies with the regulatory requirements. Mumbai-400094 for approval. This can be achieved by providing Closed Circuit TV System (CCTV). which can be achieved by either having a spare Closed Circuit TV System (CCTV) or by using mirrors and an observation window of appropriate dimensions and at a convenient height from the floor must be provided in the interloacked door for observing the patient conveniently from the operator’s position. the thicknesses may be reduced in inverse proportion to the ratio of the densities. ii. Plan approval: It is recommended to prepare the layout drawings (to scale) as per the standard layouts prepared by AERB and submitted to the Head. The first step to establish a Radiotherapy facility is to submit the layout plan of the radaition installation and get it approved from AERB from radiation safety standpoint. Textbook of Radiological Safety AERB Specification for the Layout of Radiotherapy Facility To establish a Radiotherapy facility. Medical Physicist (s) Room etc. However. In case hematite concrete is used. Niyamak Bhavan. The room layout plans (to scale 1: 50) and the site layout plan (to scale 1: 500) must be prepared and sent along with the filled in proforma AERB/RSD/RT/PLAN to the Head. the Supplier of Radiotherapy Equipments and Architects to prepare the layout plan of the Radiotherapy facility. iii. 194 . Radiation Oncologist(s) Room. Patient Waiting Area. Radiological safety Division. Site selection: The location of the radiotherapy installation should be so chosen that it is away from unconnected facilities and is close to the related facilities such as Simulator Room. iv. AERB for approval. No regulatory clearance is issued for establishing the radiotherapy facility by AERB.35 gm/cc. Construction material: The construction material to be used for radiotherapy room should be concrete of density 2. The standard layouts are advantageous as they allow structures to be built in future around the installations without any modification. where structural requirements so demand. Radiological Safety Division. It is advisable to take services of experienced Radiation Oncologists. Medical Physicists. Mould Room. the user institution must go through the Regulatory requirements as mentioned in the Atomic Energy (Radiation Protection) Rules. i. 2004 and AERB Safety Codes (AERB/SC/MED-1 and 3). Anushaktinagar. Treatment Planning System Room. The standard layouts are prepared based on typical workload for various facilities and for full occupancies around the installation from radiation safety standpoint. Viewing system: For observing the patient under treatment and the gantry movement from the control room (in case of teletherapy) appropriate viewing system must be provided. vi. conduits of minimum diameter consistent with the requirement and making an angle between 20° to 45° with the horizontal should be provided. This door should be so interlinked to the control panel by electrical interlocks that the unit cannot be operated when the door is open. In case split air conditioners are to be provided in the radiation therapy room. Any conduit required in the maze wall can be parallel to the floor at a height of 15 cm to 20 cm from treatment floor level. Moreover. In the case of accelerator installations special ventilation arrangements are required. may be a collapsible grill door or any other type as per requirement. The opening of these conduits in the treatment room should be at a height about 1. It is desirable that the control room is also air conditioned. which is provided to keep the control panel as well as the treatment room secured. In case central air-conditioning is to be provided in the radiation therapy room. Conduit: A conduit of 5 cm diameter should be provided in the wall as shown in the standard drawings to enable cables of radiation measuring instruments to pass through from the control room to the treatment room. The length may be decided in consultation with the firm installing the air conditioners and should be such as to permit efficient functioning of the air conditioners. The door opening to control room. vii. Air conditioners for the control room may be located anywhere in its brick walls as per convenience.5 m from the floor of treatment room. Altoght it is not common nowadays. The lower end of the conduit should be located in the treatment room at a height between 15 cm to 20 cm from the inside finished floor level. the ducts for central air conditioning should be taken along the wall of the entrance door and left at the desired location without making any opening on any wall. The details may be finalized in consultation with AC Engineers. 195 . The dimensions should be the minimum required for fixing the air conditioners. Door interlock: The door leading to the treatment room may be an ordinary wooden door of width 150 cm. it must be provided on the secondary walls(not on the primary wall) in case of teletherapy installation. The conduit should be fixed in the specified wall at an angle between 20° to 45° to the horizontal. The thickness of the baffle must not be less than 30 cm of concrete and width of the baffle and the length of its vertical portion should be such that 30 cm wide overlap is available all around the openings. Regulations and Dose Limits v. Air conditioning: The treatment room should be air-conditioned. the lower end of the openings should be located at a minimum height of 250 cm from the floor level outside and should further be covered with a baffle arrangement. if window air-conditioning is to be provided in the radiation therapy room. The ramp is also useful in future during source replacement operation. conduit etc. This difficulty can be circumvented by installing a teletherapy unit with a beam stopper. which is to be carried out once in every 5-7 years. relative to the radiotherapy room. Textbook of Radiological Safety viii. x. a new cobalt-60 source is brought in a transport container weighing 2-3 tons. xiv. It may also be ensured from the supplier of the unit before starting construction work that the maze/labyrinth provided in the drawing is adequate for the movement of the various components of the radiotherapy unit with or without crates. doctors room. etc. xii. Other requirements: Electrical ducting requirements and also any pit. Associated facility: Associated and supporting facilities of the radiation therapy department include simulator room. ix. This container is to be unloaded from a truck and taken into the telecobalt room. The institution must show all these facilities in the installation site plan. Ramp: In case of Telecobalt installations. should be decided in consultation with the firm installing the unit. For this work. xi. physicists room. a ramp may be provided in close proximity to the teletherapy installation to facilitate easy movement of the crates carrying the unit to the teletherapy room. xiii. . examination room. before commencement of the actual construction work. The height and slope of the ramp should be so adjusted that the transport container can be unloaded with ease from the truck and transported into the teletherapy room on a suitable trolley. This may be decided in consultation with the firm installing the unit. load specifications. The beam stopper completely intercepts the primary beam and reduces its intensity approximately by a factor of 1000 and thereby decreases the shielding requirements for the primary barrier. it is difficult to meet the shielding requirements of a teletherapy installation due to structural and space constraints. Warning lights: A red warning light should be provided above the interlocked door and should be so interlinked to the control panel that the light glows when the source is in the ‘ON’ position. treatment planning system room and mould room. Beam stopper: In certain instances. Starting construction work: No construction work should be undertaken by the institution unless prior approval of AERB for the 196 specific layout of the installation has duly been obtained by the institution. This situation may arise when (i) a teletherapy unit is to be installed in an existing room. (ii) a stationary telecobalt unit in an existing installation is to be replaced by a rotational telecobalt unit or (iii) a telecobalt unit is to be replaced by an accelerator. Construction restraints: It may be necessary for the installation of the unit that some portion of the wall or ceiling be constructed after bringing the crates carrying the unit into the treatment room. Dose Philosophy The aim of radiation protection should be to prevent deterministic effects and to limit the probability of stochastic effects to levels deemed to be acceptable. b. Scientists with these agencies have determined acceptable dose limits for the radiation worker. • Every effort shall be taken to reduce the dose to As Low As Reasonably Achievable (ALARA). (i) by setting limits well below threshold dose to deterministic effects. 197 . Committees of scientists in the field of radiation science and biology periodically review the literature and. Dose limits • The equivalent doses to individuals result in from above practices should be subjected to dose equivalent limits. In order to minimize the biological effects associated with radiation. a. Optimization • All exposures which are justified shall be under taken with a minimum possible dose. These groups include the National Council on Radiation Protection (NCRP). ICRP-60 (1990). dose limits and administrative control levels have been established. c. • No practice shall be adopted unless it produces a net positive benefit. This could be achieved. These groups provide only recommendations without the force of law and do not enforce or establish radiation safety policy. recommend changes in the dose limits. taking into account the economic and social considerations. No clinical evidence of harm would be expected in an adult working within these limits for an entire lifetime. The Justification principle The Optimization principle The Dose limitation. • These are aimed at ensuring that no individual is expected to radiation risks that are judged to be unacceptable from these practices in normal circumstances. As a general approach. and (ii) the probability of stochastic effects could be reduced by limiting exposures As Low As reasonably achievable (ALARA). the International Atomic Energy Agency (IAEA). and the American National Standards Institute (ANSI). the International Commission on Radiological Protection (ICRP). three principles designed to control radiation exposure are. Regulations and Dose Limits DOSE LIMITS Several scientific groups provide information and recommendations concerning radiation safety. Justification • All exposure either diagnostic or therapeutic shall be under taken only if the benefit gained out weighs the detriment. if indicated. (0. mSv/year Effective Dose 50 1 Eye Lens 150 50 All others (Skin. breast. higher on stochastic effects) effective dose limit and values provided that the 100 mSv in 5 y cumulative annual average over 5 y effective dose limits) does not exceed 1 mSv) Eye Lens (Based on 150 15 deterministic effects) Skin (skin 100 sq. extremi.3: Dose limits. b. 500 50 ties. The cumulative dose over a block of five years shall not exceed 100 mSv 2. and feet (Based 500 50 on deterministic effects) Fetus 2.1990) Application Occupational.cm) 500 50 (Based on deterministic effects) Hands.lung. 2001) Workers 1. Textbook of Radiological Safety The Tables 7.1987) Application Occupational. Government of India. The effective dose in any calander year during a five year block shall not exceed 30 mSV.4 list the ICRD and NCRP dose limits for various applications of radiation. mSv/year Public. The equivalent dose in any calendar year to the lens of the eye shall not exceed 150 mSV. Table 7. after diagnosis —— *Averaged over any 5 consecutive years. a. The maximum effective dose limit is 50 mSv/ year Note: 1mSv= 100 mRem Table 7.(NCRP-91.) Embryo-Fetus 5.2: Dose limits (ICRP -60.5 mSv per month) —— Dose limits (AERB.the hands and 198 feet shall not exceed 500 mSv. 3. . mSv/year Effective Dose (Based 20* (50 mSv annual 1 (if needed. followed by Government of India (AERB) dose limits. The equivalent dose in any calendar year to the skin.2 and 7. mSv/year Public. etc. • The public is already being exposed to risks in their own occupations. Why the Public Dose Limits is less? For a variety of reasons. provided that the effective dose averaged over a 5 year period does not exceed 1 mSv/y. Dose Limits to Patients Dose limits do not apply for radiation exposure of patients. In special circumstances. supervision. and a weekly shielding design limit of (P) of 0. recommends a fraction of one-half of that effective dose (E) value. the conceptus shall be protected by applying a supplementary equivalent dose limit to the surface of the womens abdomen (lower trunk) of 2 mSv for the remainder of the pregnancy. • It is not the decision or choice of the public that they be exposed. workers are exposed only during their working lifetime and presumably only while on the job. Safe limits are determined only for the staff and not for patients. and monitoring afforded radiation workers. Regulations and Dose Limits 4. Justifications for this approach include the following: • The public includes children who might represent a group at increased risk and who may be exposed for their whole lifetime. a higher value of effective dose is allowed in a single year.1 mGy 199 . or 5 mSv /y. In case of women worker of reproductive age. The employment shall be of such type that it does not cary a probability of high accidental doses and intakes.Internal exposures shall be controlled by limiting intakes of radionuclides to about 1/20 of ALI. • The public may receive no direct benefit from the exposure.once pregnancy has been established. Trainess 5. When it has been decided that a medical procedure is justified. since the decision to use radiation is justified depending upon the individual patient situation. • The public is not subject to the selection. dose limits for the general population are set lower than those for radiation workers. • The public is exposed for their entire lifetime. The effective dose in any calendar year shall not exceed 1 mSv. Public 6. This means that the conditions should achieve the clinical purpose with the appropriate dose. the procedure should be optimized. Radiation Limits for Shielding Design NCRP 1993. 7. The effective dose in any calendar year shall not exceed 6 mSv. This recommendation can be achieved for the medical radiation facilities with a weekly shielding design limit of 0.02 mGy air kerma for uncontrolled areas. a design dose limit of 6 mSv/y is used for controlled areas.3 ÷ 50) 6 μSv· week–1. Annexure-I Classification of Isotope (According to Relative Radio-toxicity per Unit Activity) Annexure-II Criteria for grading laboratories Type-I (Simple) • A simple chemical laboratory with good ventilation 200 • Two rooms.12 mSv· week–1. or (0. other limits may be applied and different barrier thickness may be calculated. one for handling and one for counting .3 mSv/y is used. In case of uncontrolled areas the effective limit shall not exceed 1 mSv/y. In the United Kingdom. Depending on local regulations. then the dose will be distributed evenly throughout the year and the weekly dose limit will be (6 ÷ 50) 0. If no special procedures are to be performed. Textbook of Radiological Safety air kerma for controlled areas. For public areas a design limit of 0. A general list is given below • Special table. Regulations and Dose Limits • Contamination Monitor • Ordinary storage (with security) • Sink – ordinary • Table surface to be covered with smooth non-absorbent material • Remote handling tongs • Propipettes / Remote pipettes • Foot operated dustbins. Hand and clothing monitor • Pocket monitor • Whole Body Counter • Personnel Monitoring Badges • Bioassay • Dilution and Distribution room • Decontamination room • Respirators 201 . Glove box. scale and type of operation with the radioisotopes. floor and wall surfaces • Proper ventilation • Storage safe – concrete/steel/lead • Stainless steel sink (elbow/foot operated tap) • Fume-hood with absolute filter incorporated near the junction of hood and ventilation duct • Contamination Monitor and Radiation Surveymeter • Air/Alarm monitor • Foot. Surgical gloves • Remote handling tongs • Propipettes / Remote pipettes • Foot operated dustbins. floor and wall surfaces • Proper ventilation • Storage safe – concrete/steel/lead • Stainless steel sink (elbow/foot operated tap) • Fume-hood with special exhaust system • Contamination Monitor & Radiation Surveymeter • Personnel Monitoring Badges • Planned radioactive waste disposal methods • Face mask. the actual facilities required by the user will be determined. Type-II (Medium) • Three rooms/more – storage. preparation and one/more handling rooms • Special table. Type-III (Stringent) Large-scale laboratory – multiroom complex with clear segregation of areas based on use. Technical Co-ordination & Logistics. 4. 3. Mumbai – 400 094. purpose of use. Anushaktinagar.N. in which the sources will be handled. specifying clearly therein the name of the authorised person(s). Textbook of Radiological Safety • Shoe barrier • Master-Slave manipulator • Planned radioactive waste disposal methods • Foot operated dustbins. Annexure-III Required procedures for expeditious supply of radioactive material for research users handling unshielded sources 1. Specify the nature and quantity of radionuclides available with your department / institution on the date of placing orders for radionuclides with the Senior Manager. All orders/requests for NOC of radionuclides should be routed through the Head of the institution/department. normal chemical operation etc. Specify clearly the type of operation with radionuclide to be procured (eg.Purav Marg.) At the time of ordering for the radionuclide with BRIT/requesting No Objection Certificate (NOC) for importing the radionuclide. C-14 and S-35 wear individual personnel monitoring badges. The institution/department is recommended to evolve an efficient record keeping system in respect of radionuclides stored/handled. mode of disposal. etc. 2. person(s) handling. date of procurement of radioisotope along with activity on that date. CTCRS. Board of Radiation & Isotope Technology (BRIT). BARC. Annexure-IV Classification of research institutions using unsealed sources Group of Prescribed limit for handling radionuclides radionuclide * Type-I Type-II Type-III I ≤ 5 µCi ≤ 5 mCi > 5 mCi II ≤ 50 µCi ≤ 50 mCi > 50 mCi III and IV ≤ 500 µCi ≤ 500 mCi > 500 mCi 202 . Mumbai – 400 094. 5. This shall be made available to the officials of this Division while conducting the radiation protection survey of the laboratory for verification.who will be handling the radionuclides and the department. The institution shall ensure that all radiation workers in laboratories handling or are likely to get exposed to radiation from radionuclides other than H-3. Deonar. V. Personnel Monitoring Section. complex wet operation. These can be had from the Head. simple dry operation. AERB/ SC/MED-1. 5. Publication 60.1990 Recommendations of the ICRP. simple chemical 1. 3. 1.1). 203 .10 Simple dry operations Manipulation of powders and volatile 0. 2. 2004:Published in the Gazette of India: September 11. Chilton (2002). 2004. Oxford (1991).00 preparations Complex wet operations With risk of spills 0. AERB safety code: Nuclear medicine facilities. Atomic energy (Radiation protection) Rules. 7. NRBP-W14. AERB/SC/MED-4(Rev. National radiological protection Board. Doses to patient from medical x-ray examinations in the UK: 2000 review. AERB safety code: Medical Diagnostic X-ray equipment and installations: AERB/SC/MED-2 (Rev. AERB/ SC/MED-3. AERB safety code: Brachytherapy sources equipment and installations. AERB safet0y code: Telegamma therapy equipment and installations.1). 6. Regulations and Dose Limits Modifying factors according to type of operation Type of operation Example Modifying factor Normal chemical operations Analysis. International commission on radiological protection.01 BIBLIOGRAPHY 1. 4.10 radiioactive compound Dry and dusty operations Grinding 0. Pergamon press. Lead Apron The lead apron should have a lead equivalent thickness of 0. gonad shield and lead glass. including the patient. to be adhered to achieve complete safety. when the X-ray tube is operated.1). Usually it is made up of rubber material to provide flexibility and handling (Fig. sufficient protective devices should be offered to the personnel. ceiling mounted barriers etc. Aprons protect the torso of the body and are available wrap around designs. there are certain personnel requirements. The attenuation offered by the lead apron is as follows: • 0. Chapter 8 Personnel Protection DIAGNOSTIC RADIOLOGY The personnel working in the radiological departments should receive exposures well below the regulatory limits on the lines of ALARA principle. In addition. 8.25-0. RADIOGRAPHY Protective Devices Personnel protection may be achieved by using several protective devices and adopting good work practices. Hence. It should also maximize the distances between the worker and radiation sources. and provide the use of appropriate shielding when working with radiation sources.1: Lead apron . This safety should cover all the personnel including staff. especially in radiography and fluoroscopy imaging. patient and public.25 mm: >90% scattered radiation is attenuated Fig. These devices should include lead apron.5 mm. 8. All individuals working in the radiation room must wear a lead apron. equipment and work practices are so designed to minimize the time with radiation sources. Hence the training. thyroid shield. responsibilities. This is to protect the back side when the worker is exposed to scattered radiation. 2A) is made up of lead and wraps around the persons neck. suitable shielding material should be used to shield the organs of interest or critical organs. depending upon the content of the lead.2B). the head and neck. Protective gloves made up of 0. 8. Personnel Protection • 0. it weighs 50- 100% more than the 0. Organ Shield Whenever required. It offer protection similar to that of lead apron. Lead glass or leaded acrylic shields are transparent and often provide greater attenuation than lead aprons. thyroid and eyes. The ceiling mounted system is counter balanced and easily positioned. 8. The lead aprons do not cover the arms.5 mm lead thickness. These devices are placed between patient and the personnel in the room. may offer protection to the hands (Fig. A B B Figs 8. For example when limb (hand) is 205 . Hence. Thyroid Shield and Lead Glass Personnel can wear thyroid shield and lead glasses for protection in the imaging room. lower legs. Lead glasses attenuate the X-rays about 30-70%.2A and B: Thyroid shield and protective gloves Ceiling Mounted Barriers Ceiling mounted barriers are used in cardiac catheterization laboratories and interventional imaging works. The thyroid shield (Fig. Normal.25 mm thickness. There are some design(Skirt-vest) which put much weight on the hips instead of the shoulders.5 mm: 95-99% scattered radiation is attenuated. The weight of the apron become the limiting factor in the ability of the radiologist and other workers to complete the examination. the weight is a major concern in the lead glass. Though higher thickness aprons offer greater protection. It is a great matter of concern in fluoroscopy. lead glasses used in the hospital may offer 20% attenuation. In no instance shall the holder’s body be in the useful beam. The gonad shield should have a lead thickness of 0. When complex examinations involving X-rays are referred. 8. Textbook of Radiological Safety X-rayed lead apron may be provided to the patient. Hospital personnel should not hold the patients during imaging procedure. Protection in Radiography The goal of diagnostic radiology is to have optimal balance between image quality and dose to the patient. The X-ray room shall be kept closed during the radiation exposure. can be about 50 %. Overcrowding should be avoided. There is a need for standardization of techniques and procedures and optimization of protection measures. one has to find the truthfulness of the 206 reference. The eyes should be shielded for X-ray examinations involving high absorbed doses in the eyes. This is very important when multiple X-ray examinations are needed. No person should routinely hold patients during diagnostic examinations. The use of gonad shield can reduce the absorbed dose in the testes by up to 95%. The use of the posterior-anterior projection rather than the anterior- posterior projection can reduce the absorbed dose in the eyes by 95 %. Any request for X-ray imaging needs to be justified. on benefit vs risk point of view. Shields should not interfere with the anatomy under investigation. Work Practice Occupancy in the Room Only persons whose presence is necessary should be in the imaging room during the exposure. Absorbed dose in the eyes can be reduced by 50-75 % by shielding the eyes.5 mm of lead. Such persons shall be provided with protective aprons and gloves. All such persons must be protected with lead aprons/shields.3)can be provided to the patient to protect the gonads from primary beam. Assistance to Patients Holding of children or infirm patients for X-ray examination shall be done only by an adult relative or escort of the patient.3: Gonad shield ovaries. Similarly gonadal shield (Fig. and should be as far away from the primary beam as possible. In no case shall the film of X-ray tube be held by hand. while the reduction of absorbed in the Fig. . such as conventional petrous bone tomography. Immobilization devices (Mechanical supporting or restraining devices) shall be used to prevent movement of children during exposure. certainly not those who are pregnant or under the age of 18 years. 8. 025 mm (Rh target).g. Whereas the low energy X-rays are absorbed in the first few cm of tissue. ii. carbon fiber) materials for cassette fronts. rare earth. As the filtration is increased. Filtration also decreases tube output and hence an optimal filtration is required for each X-ray unit. Hence. patient exposure can be reduced by using a higher kVp and lower mAs. Whereas Mo can not be used as filter in mammography X-ray tubes with Rh targets. Mo target with Rh filter is commonly used.0 mm Al between 70 and 100 kVp • 2. the beam become hardened and decreases the image contrast.03 mm (Mo target) • Be 1 mm + Rh 0. Field Area Reduction of the field size by collimation is another important dose reduction technique. and there by reducing patient dose and skin injuries. Mammography • Be 1 mm + Mo 0. General radiography • 1. Hence. one has to balance between patient dose and image contrast. Filtration can remove selectively low energy X-rays. The scatter incident on the detector also decreases. there by increasing the radiation dose to skin. The high energy X-rays transmit through the patient and contribute to the image formation. This means that the absorption is lesser in the patient even though the exposure / mAs is higher. In mammography. Field size reduction reduces the scatter there by reducing the dose to adjacent organs. Tube Voltage (kVp) Increasing kVp result in greater transmission of X-rays through the patient. low attenuation (e. 207 . Constant potential / High frequency generator can reduce dose significantly. The best way to reduce patient dose is reduction of mAs. Diagnostic X-ray consists of both low and high energy X- rays.5 mm Al below 70 kVp • 2. antiscatter grid interspacing and table tops and grid removal etc. 400 speed for pediatric). The other methods are use of fast screen-film combination (e. As a rule of thumb. minimal field size to cover the patient volume is sufficient.g. But this will reduce the image contrast due to higher effective energy of the X-ray beam. The recommended beam filtration is follows: i. Filtration A filter is a metallic sheet introduced in the path of X-rays in order to reduce patient dose. Personnel Protection Equipment and Peripherals Patient dose can be reduced by selecting optimal equipment and its peripherals.5 mm Al above 100 kVp. 4A and 8. the rule of thumb is “use smallest possible field size and good collimation”(Fig. 8. 208 Figs 8.4A and B: Field size and dose reduction .4B). Textbook of Radiological Safety resulting in improved image contrast. Hence. the gonads should be kept outside the X-ray beam by carefully adjusting the X-ray field.5). Increased SOD also facilitate reduction of patient exposure due to tube leakage. In radiography projections. there fore longer SID has clinical advantages. When the SID is less than 100 cm. the absorbed dose in the testes can be one-fourth or less of that when testes are in the field (Fig. This will enable us to decrease the integral dose. Increasing the source to object distance (SOD) and source to image distance (SID). the SOD should be not less than 45 cm. therefore increase of SOD is the only way of 209 .5: Change in absorbed dose in testes with distance between edge of the X-ray field and testes Source to Object Distance The radiation intensity from a point source varies inversely as the square of the distance from the source. In radiography and fluoroscopy with stationary X-ray equipment. 8. and therefore the mass of the skin and internal tissues irradiated. 8. which reduce the volume of patient irradiation. increases the radiation intensity sharply at the surface of the patient (Fig. Fig. When the testes are located just a few centimeters outside the X-ray field edge. since the tube is away from the patient. As the SOD/SID is increased there is a reduced beam divergence. Photofluorography and radiography of the chest should be performed with a SID of at least 120 cm. the quality of the diagnostic information becomes poorer. 8. Personnel Protection The decrease in X-ray field size also reduces the total radiation energy delivered to the patient.6). will reduce the patient dose. Where as decrease of SOD. In the case of C-arm units fixed SID is used. in place of conventional materials. allows transmission of a larger proportion of the X-ray beam. Image Receptors The speed of the image receptor determines the number of X-ray photons necessary to produce an optimal image signal. the skin to image receptor distance is constant at 25 cm Carbon Fiber Materials The use of carbon fiber materials for the patient support. but limited by image quality. Faster film increases the quantum mottle and faster screen (thick) decreases the spatial 210 resolution. anti scatter grids and radiographic cassettes. . The overall reduction of absorbed dose in the skin of the patient facing the X-ray tubes. At an X-ray tube voltage of 80 kV. This is directly related to the patient dose. is in the range of about 30 % to more than 50%. higher speed film-screen reduces the patient dose. the use of carbon fiber materials enables the absorbed dose in the skin of the patient to be reduced. and decreases the patient dose. the percentage reductions in absorbed dose in deeper tissues will be similar. Thus. Higher speed (400) system require less exposure to produce the same optical density. 8. Fig.6: Dependence of absorbed dose in the skin on the distance from the X-ray source. Textbook of Radiological Safety reducing patient dose. in anti scatter grids and for the radiographic cassette face. If the X-ray tube voltage is not changed. Hence in fluoroscopy minimum distance between source and the patient must be not less than 30 cm. from the combined use of carbon fibre materials in patient supports. speed 75-100). Whereas in pediatric imaging increased speeds (e. and periodic maintenance of automatic processors may also help to reduce repeat X-rays and patient dose. These systems allow post processing methods. Therefore. In addition. Hence. Hence. The PSP receptor system is equivalent to 200 speed screen-film system in terms of quantum mottle and noise for adult abdomen and chest radiography. In digital image receptors. Personnel Protection Computed radiography (CR) uses photostimulable storage phosphor (PSP) detectors and the digital radiography (DR) receptors have wide latitude.g. Under exposed images are associated with high quantum mottle and poor contrast resolution. one can not notice this adverse effect on image quality. Conventional screen-film has inherent safety feature. This will increase the patient dose. 8. In the case of extremities imaging. to manipulate image density for optimal viewing. Over exposed images contribute higher patient dose. reduction of repeat films can also reduce patient dose significantly. and 4 mR per image for digital subtraction angiography. They compensate for under or over exposure and reduce retakes. One can easily identify this and carry out necessary remedial measures. higher patient exposures may go unnoticed. proper darkroom procedure. To reduce patient motion (i) short exposure times. Patient Motion Patient motion is a matter of concern in diagnostic imaging. breast and eyes (Fig. Proper instruction to the patient. Patient Positioning The collimator is adjusted to exclude radiosensitive organs such as gonads.g. or distracting devices should be applied and adopted. which may increase repeat X-rays. the film reject rate due to all causes should be kept below 5%. It may cause motion artifacts. Image Intensifier The image intensifier has wide dynamic range and the entrance exposure is controlled by light limiting aperture or electronic of the subsequent detector (e. If high kV is used the film becomes over dark. the CR should be used at higher exposure levels (e. digital image receptors require strict quality assurance check.7). (iii) entertainment. since it is adjusted in post processing. 211 . there by increasing the patient dose. TV camera). (ii) use of immobilization or sedation. 400) is recommended.The entrance exposure is 1mR per image in fluoroscopy. checking the factors before exposure. Any reduction in exposure is limited by quantum mottle.g. For example.6 13. delivers an exposure of 6 R at 1 m.1: Radiation dose in various imaging systems EXAM Radiography (mGy) Fluoroscopy (mGy) CT (mGy) Chest 0. 2 mA. 80 kVp. and (B) correct positioning PROTECTION IN FLUOROSCOPY Fluoroscopy imaging contributes large portion of dose in medical imaging due to continuous X-ray production and real time image output. Table 8. The patient dose also depends upon the angulation of the beam through the patient. Exposure rates are greater in lateral examination than that of anteroposterior. Cini angiography studies employ high exposure rates of 20 to 70 R /min with short exposure times. Textbook of Radiological Safety Figs 8.1. Then the skin entrance exposure will be: 2 ⎛ 100 ⎞ Entrance exposure = ⎜ ⎟ × 6 = 67 R ⎝ 30 ⎠ Thus. a fluoroscopy imaging involves a technique of. Though the exposure technique are moderate (3 mA. Some systems have turbo mode where the exposure rate may exceeds 20 R/min and hence this mode should be used judiciously.14 3.7A and B: (A) Wrong positioning.53 6. The entrance exposure of various imaging systems like Radiography.4 21.10 min on time. in fluoroscopy the entrance dose is higher.5 212 .2 Abdomen / pelvis 0. fluoroscopy and CT scan are given in Table 8. 80 kVp). the examination on time extend from minute to hours. 3.6. it also increases the patient dose and hence used sparingly. It is easy to identify the patient who may be at risk. Intensifiers are available in different sizes (4. to minimize skin injuries. Use of optimal image intensifier system (conversion gain. Maintaining much distance between the X-ray tube and patient will also reduce the skin dose. to view the image even after the exposure. Pulsed fluoroscopy reduces dose by allowing frame rates lesser than real time. Personnel Protection The source to object distance should be not less than 30 cm. high contrast ratio. physician training plays an important role in dose reduction methods. Dose -Area –Product (DAP) meter should be used to measure the dose in fluoroscopy. Dose Reduction in Fluoroscopy The most important method of dose reduction in fluoroscopy is to limit the beam ON time. spatial resolution and contrast sensitivity) can also reduce the patient dose. by using short burst of exposures. The patient entrance dose is limited to a maximum of 10 R / min. and 1.8: Dose area product meter 213 . The ionization signal generated is proportional to the beam area. then patient dose can be estimated. due to radiation. 8. Fig. beyond the collimator (Fig.2 mm) to handle adult and pediatric patients. It is a radiolucent ionization chamber positioned across the primary beam. 8. This is a suitable technique in patients where higher temporal resolution is not required. 0. Though magnification technique improves spatial resolution. If the DAP meter is calibrated with field size. This will reduce the fluoro time by 50-80% in many procedures. It may be used along with digital image memory to reduce patient dose. and 5 R / min without AEC. source to object distance (SOD).5. Real time display of patient dose can help the physician to modify the procedure. with automatic exposure control (AEC). One can also use the last image-hold facility. Hence. Reducing the field size by collimation will also reduce the integral dose. source to detector distance (SDD) and collimation. and 12 inch) and proper selection of intensifier mage size to match a specific institution is very important. The X-ray tube is provided with multiple focal spots (0.8). 9. 8. CT scan is the major contributor of patient dose. USA has issued a public health notification (2002) regarding CT scan dose reduction that includes: i. 8. (increases the image noise). Fixed techniques in CT may lead to unnecessary patient dose. but provides 48% of the population’s collective dose (US data) as shown in the Fig.9: Frequency distribution of medical imaging and patient radiation dose in % The Food and drug administration (FDA). the training of the technologists is very important in CT scan imaging. by reducing mAs for thinner patients.9. 214 iii. Increase pitch or table increment (increase the effective slice thickness). e. ii. In CT scans automatic exposure modes are not available.g. Textbook of Radiological Safety PROTECTION IN COMPUTED TOMOGRAPHY Computed tomography (CT) is a valuable and life saving imaging tool in medical imaging. This will compensate the thickness variation in torso of body from AP to lateral projections. . Therefore. Most CT scanners use fixed kVp and mAs regardless of patient size. Few models now offer modulation of mA as a function of rotation angle. Use noise reduction algorithms. children. It performs 8 % diagnostic issues. He should know the way of reducing patient dose. which will reduce the patient dose. Fig. Reduce tube current. neonatal. 300 mAs. for creating a good quality image of a 32 cm torso. vii. Increasing numbers of radiological examinations are being performed in infants and children.2 4 20 2. For a 30 cm patient about half of the mAs (160) is sufficient to produce the same quality of image. but increases the noise and slice thickness. vi. 5 mm slice. with proper selection of mAs for each patient. A pediatric radiological procedure should be individually planned and projections should be limited to what is absolutely necessary for a diagnosis. Personnel Protection iv. Hence. Children are 10 times more sensitive to 215 . Table 8.2). imaging techniques that do not use ionizing radiation should always be considered as an alternative. Eliminate inappropriate referral. Develop and use a chart or table of tube-current settings based on patient weight or diameter and anatomical region of interest. 5 mm slice and pitch 1. the technical chart is very useful to reduce patient dose. optimal balancing is necessary in devising the techniques. Therefore. when adult settings are used.9 24 26 15 45 30 53 160 32 100 300 34 188 564 36 352 1.2: Technique chart (120 kVp. mA and thickness of the patient (Table 8. Thus. Millions of children undergo high dose procedures such as computed tomography and interventional procedures. Pediatric protocols. A technical chart can be devised involving kVp.058 Children are more vulnerable to the late somatic effects and genetic effects of radiation than adults (epidemiologic study).2 7 (43% dose!) 22 4.3 1 16 0. Children receive a higher dose.2 13 24 7. The reduction of current and increased pitch though reduces the patient dose. which reduces the patient dose by 43 %. For a 20 cm patient only 7 mAs is required. Reduce the number of multiple scans with contrast material. The chart is devised with 120 kVp.6 2 18 1. PROTECTION IN PEDIATRIC IMAGING Children have higher radiation sensitivity than adults and have a longer life expectancy (larger window to express radiation damage). v. Pitch = 1) Patient diameter (cm) % mAs mAs 14 0. 300 mAs. The Risk for developing a radiation–related cancer can be several times higher for a young child compared with an adult exposed to an identical technique. (iii) Field size reduction (Collimation). ii. .g. Pediatric Radiography Equipment and Peripherals The selection of equipment associated peripherals should suit the pediatric imaging work. Textbook of Radiological Safety radiation than adults and girls are more sensitive than boys. Vetting of referrals for complex examinations. Typical values of Entrance Surface Dose (ESD) per radiograph and Dose Area Product (DAP) for common paediatric fluoroscopy examinations are given in Table 8. thyroid and lens.3: Typical dose levels in paediatric radiology Examination Entrance surface dose (µGy) Age 0 1 5 10 15 Abdomen AP 110 340 590 860 2010 Chest PA/AP 60 80 110 70 110 Pelvis AP 170 350 510 650 1300 Skull AP / 600 1250 / / Skull LAT / 340 580 / / Dose area product (mGy•cm2) MCU 430 810 940 1640 3410 Barium meal 760 1610 1620 3190 5670 Barium swallow 560 1150 1010 2400 3170 Special Considerations Dose to the children can be reduced significantly by adopting either one or combination of the following: This includes (i) Higher kVp and lower mAs. and (iv) constant potential/High frequency generator. This includes (i) fast screen-film combination (e. 400 speed for pediatric). iii.3. Hence. anti-scatter grid interspacing. iv. and (vi) Posteroanterior projections in female patients.g. one has to examine the following issues before carry out the imaging: i. (v) Increased Source-Object Distance (SOD). Radiation Risks in children is a public health issue. rare earth. table tops. Table 8. so that the radiation dose will be lesser. Standardization of techniques and procedures. (iv) Shielding 216 of gonads. (iii) grid removal. Justification of requested examinations. (ii) low attenuation (e. Optimization of protection measures. (ii) Increased filtration. carbon fiber) materials for cassette fronts. and (iii) incorporation of entertainment.10). or distracting devices. 8. • Shielding devices should be appropriately positioned to be efficient for protecting the tissues for which they are placed and to avoid unnecessary repeat examinations. when required. • The radiation beam should be limited using collimation. (ii) Immobilization or sedation of the patient (Fig. if possible.10A and B: Immobilization of child during chest radiography (For color version see plate 3) Dose Reduction Methods in Pediatric Radiography Anti-scatter grids are normally not required in pediatric radiography as the gain in image quality does not justify the increase in patient dose. • Immobilization. . Personnel Protection Patient Motion Patient motion should be avoided during examinations under radiation. • High speed screen-film combinations should be used where possible to enable reduction in radiation exposure and exposure time. To fulfill this one can adopt the following: (i) Short exposure times. as the reduced resolution obtained is comparatively insignificant for the majority of clinical indications. • The use of Automatic Exposure Control (AEC) is generally not appropriate in children as the sensors (size and geometry) are normally designed for adult patients. Instead. exposure charts corresponding to radiographic technique. should be provided by specialized 217 devices. patient thickness in the X ray beam and presence or absence of anti-scatter grid are much safer and easier to use. except in children in their teens and when the body build is such as to increase scatter • Good image detail is achieved by maintaining a balance between the use of a small focal spot size and a short exposure time. Figs 8. There is no need for these large doses and CT settings can be reduced significantly with out losing the image quality. The effective dose from single pediatric CT ranges from 1-30 mSv. CT scans are increasingly used in pediatric imaging and mostly fixed kVp and mAs. CT in children has increased about 8 fold since 1980. The patient should be positioned as close as possible to the image intensifier. The patient dose in CT is an important issue for children as reports suggest that in some centres the exposure factors used for scanning children are the same as for adults. regardless of patient size is used. Hence.1 to 6. CT scanning contributes most collective dose from radiographic exposures due to the increasing use of this modality. The Image intensifier should have diameter of 4. so that one can have varying techniques from 100 mA × 1ms to 800 mA × 7ms. such as 70 kVp for paediatric patients and 80 kVp for adults. About 4. Some centres prefer to set a ‘floor’ (a kVp) below which the system will not go. The cine frame rate should be >60 fps. Pediatric Computed Tomography CT and interventional procedures are high dose procedures in radiology and yield higher individual patient doses than other radiological procedures do.3 mm (3-4 years child) and 0. The X-ray tube should be as far away as possible from the patient table in order to avoid excessive skin dose. on the basis of the body thickness falling in the X-ray beam.The generator should have range of mAs from 0. ii. i. Textbook of Radiological Safety Pediatric Fluoroscopy Fluoroscopy offer much higher dose to the children than radiography imaging.5 in (11 cm). when adult settings are used. iv. Children receive higher doses than necessary. The lowest frame rate acceptable and last-image-hold facility should be used. iii. with annual growth of about 10 % per year. vi. v. Hence. 218 children should not be scanned using adult techniques. optimal selection of equipments and specialized techniques are very much essential. . and one third of the children have three scans. There is a potential increase in the radiation exposure to children undergoing these scans. This is suitable for imaging children having weight from 3-140 kg at 65-75 kVp. which will triple the cancer risk. This problem is relatively lesser in interventional procedures as the machine. Additional copper filtration also reduces patient dose. automatically adjusts factors in most modern equipment. The X-ray tube should have at least two focal spots namely 0.7 million CT examinations are performed annually on children in the US. Dose reduction methods in fluoroscopy. and pediatric CT protocol or dose reduction methods should be made available.6 mm (8 years children). 74 22 S Adult 0. 200 mA.66 0.4: Patient thickness.76 0.16 Table 8.51 0.43 0. Pediatric mAs = Baseline data × Reduction factor (RF) Fig.4 and 8.49 14 5 0.5: Patient thickness. For a adult body this is about 25 mGy and head it is 75 mGy.82 25 M Adult Baseline Basline 31 L Adult 1. age and reduction factors for pediatric abdomen and thorax PA Thick (cm) Age Abdomen RF Thorax RF 9 Newborn 0.5 sec scan time. the CTDIvol can be calculated.42 12 1 0.64 19 15 0. What is the appropriate 219 pediatric technique for a 5 year old thorax at a pitch of 1? .90 0. Personnel Protection Dose Reduction Methods Using the PMMA phantom (Fig 8.59 0. age and reduction factors for pediatric head PA Thick (cm) Age Pediatric Head mAs RF 12 New born 0.86 17 5 0.11). 0.11: ACR accredited PMMA Phantom (For color version see plate 3) Table 8. Taking these as baseline data.57 16 10 0.25 1. pitch=1and FOV=35 cm.74 16 1 0. 8.93 19 M Adult Baseline Example 1: An adult thorax is examined at a technique of 120 kVp. The pediatric protocol is obtained as follows: Table 8. dose reduction factors can be designed.5 presents the reduction factors for pediatric abdomen and thorax and head respectively. ACR CT Accreditation program. However. Radiologists and physicians should be aware that images with low noise.57. pitch=1 and FOV=25 cm.4 the RF for 5 year old thorax is 0.6 Table 8.6: Pediatric organ and effective doses with normal and adjusted mAs for head and abdomen examinations Exam Organ Organ dose Efective dose (mGy) (mGy) Head (200 mAs) Brain 23-49 1.9 Abdomen (200 mAs) Stomach 21-43 11-24 Abdomen (50 mAs adjusted) Stomach 5-11 3-6 Dose Reduction Methods in Paediatric Chest CT i. . Example 2: An Adult head is examined at a CT technique of 140 kVp. In general a head examination with adult protocol (200 mAs) may give 23-49 mGy organ dose in brain.9-1. Many authors suggest using 100 to 200 mAs settings for high resolution chest CT in children. 0.8 Head (100 mAs. may provide the diagnostic information. 400 mA. Similarly the abdomen dose reduces from 21-43 mGy to 5-11 mGy if the mAs is adjusted as shown in the Table 8. then Pediatric mA = Baseline × RF = 400 mA × 0. iii. If the mAs is adjusted to 100 and dose become 11-25 mGy. Awareness on this can help in significant reduction in patient dose.86.86 = 344 mA. Textbook of Radiological Safety From the Table 8.8-3. ii. There is lack of consensus on kVp reduction in CT examination. even if they do not look very crisp.57 = 144 mA. What is the appropriate technique for a one year old head? From Table 8. reliable diagnostic studies can be obtained using much lower mAs. mAs reduction at defined kVp has been used with success by many centres and is the most efficient method of dose management in children as also in adults. then Pediatric mA = Baseline × RF = 200 mA x 0.5 sec scan time. iv. adjusted) Brain 11-25 0. Image quality in CT is generally more than what is required for confident diagnosis.5 the RF for a one year old head is 0. In cooperative children who are able to breath-hold as low as 34 mAs can be used and in non-cooperative 220 children 50 mAs. In addition. If possible. they should be shielded. however. result in significant fetal harm. can. children were classified by colors based on weight and this was shown to significantly reduce scanning errors in settings for pediatric multi-detector CT. Size-based tables for abdominal multidetector CT and body CT angiography in children are available. Finally. In one study. and least in the third trimester. Prenatal doses from most properly done diagnostic procedures present no measurable increase in the risk of prenatal death. Radiation risks are most significant during organogenesis and the early foetal period. such as those involved in therapeutic procedures. Whenever radiosensitive tissues such as breast and thyroid fall within the exposed area. somewhat less in the second trimester. There are radiation-related risks throughout pregnancy that are related to the stage of pregnancy and the foetal absorbed dose. the underdeveloped tissue) protection using for example 2 mm thick bismuth coated latex shielding reduces the dose to the breast-anlage by approximately 40%. The effects of exposure to radiation on the conceptus depend on the time of exposure with respect to the date of conception and the amount of absorbed dose. imaging parameters such as kVp and mAs need to be adjusted for patient size. PREGNANCY AND RADIATION It is unlikely that radiation from diagnostic radiological examinations will result in any deleterious effects on the child. for example. but the possibility of a radiation- induced effect cannot be entirely ruled out. 221 . malformation. the use of multiphase scanning should be curtailed as much as possible. Effects on Radiation Exposure In Utero (ICRP-84) i. Higher doses. Recent technology developments include automatic tube current modulation where the tube current is adjusted according to thickness and density of tissues to maintain a constant level of image noise. ii. the examination should be tailored to answer the specific question asked by the referring clinician. pelvic scanning is not always necessary when an abdominal scan is requested and it may be possible to curtail follow-up CT exams to a specific organ. vi. MRI and US should take priority. Personnel Protection v. Breast-anlage (primordium or the first rudiment of the breast. Recent technology developments include automatic tube current modulation where the tube current is adjusted according to thickness and density of tissues to maintain a constant level of image noise. or the impairment of mental development over the background incidence of these entities. Dose Reduction Methods in Pediatric Abdominal CT Strategies should include obtaining only necessary CT examinations. During the period of ± 25 weeks post conception. In such cases. If an examination is typically at the high end of the diagnostic dose range and the fetus is in or near the radiation beam or source. however. as the irradiation will have occurred in the first 3 weeks following conception. Throughout most of pregnancy. care should be taken to minimize the dose to the fetus while still making the diagnosis. but only by a medical physicist/ radiation safety specialist experienced in dosimetry.000 mGy (1 Gy) result in a high probability of severe mental retardation. Commonly. Chest and Extremity Radiography in Pregnancy Medically indicated diagnostic studies remote from the fetus (e. but it is best to use actual data. . iv. During the same time.g. the central nervous system (CNS) is particularly sensitive to radiation. In a few cases the conceptus will be older and the dose involved may be considerable. If a calculation of radiation dose is required in order to advise the patient. the radiation dose to the fetus/conceptus should be estimated. The patient’s date of conception or date of LMP (last menstrual period) should also be 222 determined. and will naturally be very concerned when the pregnancy becomes known. Some assumptions may be made in the dosimetry. foetal doses in the range of 1. CT and Pregnancy Occasionally. Fetal doses in excess of about 100 mGy may result in a verifiable decrease of IQ. Textbook of Radiological Safety iii. The sensitivity is highest 8±15 weeks post conception. Radiation has been shown to cause leukemia and many types of cancer in both adults and children. It is. The CNS is less sensitive to these effects at 16±25 weeks of gestational age and rather resistant after that. the embryo/ fetus is assumed to be at about the same risk for potential carcinogenic effects of radiation as are children. extremely rare for the dose to be high enough to warrant advising the patient to consider terminating the pregnancy. In many cases there is little risk. a patient will not be aware of a pregnancy at the time of an X-ray examination. the radiographic factors should be noted if known. radiographs of the chest or extremities) can be safely done at any time during pregnancy if the equipment is in proper working order. The patient can then be better advised as to the potential risk involved. the risk of not making the diagnosis is greater than the radiation risk involved. Tailoring the examination and examining each radiograph as it is taken until the diagnosis is achieved and then terminating the procedure can do this. However. Selecting appropriate exposure factors. Restricting the X-ray beam size to being as small as is necessary for the clinical purpose. due care is taken to optimise how the procedure is performed so as to minimise radiation exposure to the fetus. the magnitude and type of which is a function of dose and stage of pregnancy.7). iii. moral. termination of pregnancy at fetal doses of less than 100 mGy is not justified based upon radiation risk.6000 mGy. For well performed procedures. The gonads are radiosensitive organs in the human body. putting a lead apron on the table to cut down any primary beam from the X-ray tube reaching the fetus has very little effect. Choosing the direction of the primary beam so that it is as far away from the foetus as possible. 223 . they imply no risk of sterility. It is complicated by individual ethical. but it can be reassuring to the patient and staff and thus is recommended provided the use of the apron does not compromise the performance of the procedure. each particular procedure must be clinically justified. Once justified. The issue of pregnancy termination is undoubtedly managed differently around the world. As diagnostic X-ray examinations involve small doses (Table 8. At foetal doses in excess of 500 mGy. and iv. the decision should be based upon the individual circumstances. estimated foetal doses are typically quite small. Personnel Protection Cardiac Catheterization and Pregnancy There will be many situations where the benefit of performing the procedure is much greater than any small possible harm that might arise from the radiation exposure. Many believe that this dose can cause sterility in the exposed individual. This complicated issue involves much more than radiation protection considerations and require the provision of counseling for the patient and her partner. Ensuring that the overall exposure time is as small as possible. consistent with achieving the desired clinical outcome. Some of the main methods for minimizing the dose to the foetus include: i. As a final comment.6000 mGy. and well below the level of concern for radiation effects. The threshold radiation dose for permanent sterility in men is 3500 . including in this situation taking into account when the procedure needs to occur. The radiation exposure to foetus predominantly arises from scattered radiation within the patient. At fetal doses between 100 and 500 mGy. and religious beliefs as well as perhaps being subject to laws or regulations at a local or national level. as always with any medical exposure. ii. and for women 2500 . there can be significant foetal damage. but really it is not so. Termination of Pregnancy after Radiation Exposure According to ICRP 84. 7 10 Lumbar spine 1. b) change to another area where the radiation exposure may be lower.01 Thoracic spine < 0.7 10 Pelvis 1.6 Pelvis 25 79 Continuation of Work of a Pregnant Employee in X-ray Department A pregnant worker can continue working in an X-ray department as long as there is reasonable assurance that the foetal dose can be kept below 1 mGy during the pregnancy.06 0. it is important to ensure that pregnant women are not subjected to unnecessary discrimination.01 Intravenous urogram 1. Textbook of Radiological Safety Table 8. 1998) Conventional X-ray examinations Mean (mGy) Maximum (mGy) Abdomen 1.1 4 Skull < 0. however. ii.1 5. In interpreting this recommendation.005 Lumbar spine 2.4 4.96 Head < 0. The ICRP -84 recommend the following: i. There are responsibilities for both the worker and the employer. or c) change to a job that 224 has essentially no radiation exposure. imply that the employer should carefully review the exposure conditions of pregnant women. Shrimpton.01 < 0.01 < 0.2 Chest < 0. The first responsibility for the protection of the conceptus lies with the woman herself.0 49 Chest 0. When a medical radiation worker is known to be pregnant.4 8. there are three options that are often considered in medical radiation facilities: a) no change in assigned working duties. There is no single correct answer . Restricting dose to the conceptus does not mean that it is necessary for pregnant women to avoid work with radiation or radioactive materials completely.01 < 0.7: Approximate foetal doses from common diagnostic procedures in United kingdom (Sharp. and Buiy.01 Fluoroscopic examinations Mean (mGy) Maximum (mGy) Barium meal (UGI) 1. who should declare her pregnancy to management as soon as the condition is confirmed.8 24 Computed tomography Mean (mGy) Maximum (mGy) Abdomen 8.8 Barium enema 6. their working conditions should be such that the probability of high accidental doses and radionuclide intakes is insignificant. or that they must be prevented from entering or working in designated radiation areas. In particular. It does.005 < 0. a pregnant technician can be restricted from spending a lot of time in the radiopharmacy or working with radioiodine solutions. this may involve transferring a technician from fluoroscopy to CT scanning or some other area where there is less scattered radiation to workers. Changing to a position that may have lower ambient exposure is also a possibility. factors other than radiation exposure should be considered in evaluating pregnant workers activities. In diagnostic radiology. An ethical consideration is involved in both of these last two alternatives since another worker will have to incur additional radiation exposure because a co-worker became pregnant. In spite of this. In radiotherapy with sealed sources. This approach is not required on a radiation protection basis. It would be reasonable to evaluate the work environment in order to provide assurance that high-dose accidents are unlikely. Workers in nuclear medicine and radiation therapy usually do not wear lead aprons and are exposed to higher photon energies. fetal doses are not likely to exceed 25% of the personal dosimeter measurement. Personnel Protection for all situations. and recommended dose limits. vi. or the employer may depend on her to continue in the same job in order to maintain the level of patient care that the work unit is customarily able to provide. If the dosimeter has been worn outside a lead apron. In a medical setting there are 225 . Change to a position where there is no radiation exposure is sometimes requested by pregnant workers who realize that risks may be small but do not wish to accept any increased risk. The employer may also arrange for this in order to avoid future difficulties in case the employee delivers a child with a spontaneous congenital abnormality (which occurs at a rate of about 3 in every 100 births). and in certain countries there may even be specific regulations. A personal dosimeter worn by diagnostic radiology workers may overestimate fetal dose by about a factor of 10 or more. local policies. the measured dose is likely to be about 100 times higher than the fetal dose. v. iii. Finally. There are many situations in which the worker wishes to continue doing the same job. It is desirable to have a discussion with the employee. vii. iv. viii. The worker should be informed of the potential risks. From a radiation protection point of view. In nuclear medicine departments. and it obviously depends on the facility being sufficiently large and flexibility to easily fill the vacated position. pregnant technicians or nurses might not participate in manual brachytherapy. The recommended dose limit applies to the fetal dose and it is not directly comparable to the dose measured on a personal dosimeter. this is perfectly acceptable providing the foetal dose can be reasonably accurately estimated and falls within the recommended limit of 1 mGy fetal dose after the pregnancy is declared. Efforts should optimally be directed at not involving females who are or may potentially be pregnant. ii. If it is essential to involve the help of a pregnant female. Each case must be assessed according to the gestational age when 226 exposed and the radiation levels received by the conceptus from each exposure. There are a number of national groups that have established non-radiation related guidelines for such activities at various stages of pregnancy. which may not have lead rubber protective curtains. In such circumstances. However. Consequently. Counseling of Patients Patients who have received diagnostic studies while pregnant are often alarmed because of emotional perceptions surrounding radiation. . It is unlikely that radiation from diagnostic radiological examinations will result in any deleterious effects on the child. The patient should be counseled that the risk assessment is being done not because there is reason to believe there is great risk in her circumstance but because it is one of the precautions normally taken whenever a pregnant woman receives certain diagnostic studies (Note: this applies only to diagnostic studies. iii. for some fluoroscopic examinations there is a potential for higher radiation doses to staff. the implications of the ICRP recommendations on the radiation exposure of the fetus of staff performing fluoroscopy procedures should be assessed. Textbook of Radiological Safety often requirements for lifting patients and for stooping or bending below knee level. Chance of Approaching the Dose Limits of Exposure Radiation doses to occupationally exposed staff working with radiological equipment are generally low and it is unlikely that the equivalent dose limit recommended by the ICRP will be approached. The health professionals should advise patients about the steps that will be taken for risk assessment and provide appropriate information regarding the risk associated with diagnostic (and therapeutic) radiation exposure during pregnancy. public dose limits do not apply to the family member. to patients who have received radionuclides. but the possibility of a radiation-induced effect cannot be entirely ruled out. there are situations where family members provide essential medical care. The following points should be considered: i. The risk from therapeutic studies may be severe. particular radiation protection problems arise from the extended fluoroscopy times and from the use of certain radiological equipments. such as fetal thyroid ablation). it should be done in such a way that the foetal dose from this involvement does not exceed 1 mGy. ix. either in the hospital or at home. During interventional radiology procedures. Occasionally. kidneys. image receptors and film processing systems is necessary. determination of pregnancy status are necessary before performing any kind of imaging. A precise fetal dose assessment requires numerous pieces of information about the X-ray system. Lack of automatic exposure control may also increase the repeat X-rays and technique chart of various examinations should be posted at the control panel. processor artifacts due to dirty components or contaminated chemicals. protective devices with suitable shielding . Improperly loaded cassettes. the patient size. Mammography examination should not be used as a screening procedure in patients with age less than 35-40. and other involved persons understand the circumstances and can thus make a reasonable decision regarding the management of the pregnancy. lumbar spine. The dose evaluation may take up to a week to complete. female patient of reproductive age. the radiation risk will be assessed and will be reviewed along with other possible risks of pregnancy so that the physician. This number will be higher in (i) training centers. v. When all the information is acquired. ‘typical’ fetal dose numbers should be used with the understanding that there may be a significant difference between the ‘typical’ dose numbers and the dose numbers resulting from an actual dose assessment. NUCLEAR MEDICINE PROTECTION IN NUCLEAR IMAGING Protective Devices The radiation exposure rate in nuclear medicine ranges from 100 R/hr to 227 natural background. The repeat X-ray exams ranges from 1 – 15%. Use of high speed films or DR systems in dental X-ray imaging can reduce the patient dose. This will enable the technologist to select correct radiographic technique. etc. Yearly dental check up with X-ray examinations should be avoided. unless there is a familial history of breast cancer. the examinations conducted. Personnel Protection iv. Therefore. Hence. excessive fog due to light leak or poor film storage conditions. Elimination of screening X-ray exams can significantly reduce population dose. uncalibrated X-ray unit or improper imaging techniques can also increase the retakes. Other Factors Identification of the patient. bladder and abdomens). vi. due to proper positioning difficulty. ureter. (ii) mobile X-rays(chest. the patient. thoracic spine. The retakes are monitored periodically and suitable action must be taken to improve image quality. due to lack of experience. A periodic quality assurance program to test the performance of the X-ray unit. 5 GBq) would be 6 mSv / h at 0. Textbook of Radiological Safety material should be used for personnel protection. Waste storage: Lead dust bin.0 cm lead + additional shielding of 4. a patient with 800 MBq of Tc-99m activity yield a exposure of 160 μSv / h at 30 cm. body dosimeters and lead apron.8.25 mm Pb may reduce the exposure from 160 to 10 μSv / h at 30 cm.0 μSv/h. finger ring TLD dosimeter. Radiation Dose from Patients The nuclear medicine patients contribute radiation exposure to staff and hence reasonable distance should be kept by the staff (Table 8. that includes the core shielding of 5.8: Occupational staff exposure from patients Radionuclide Half life Activity (MBq) Exposure(μSv / h at 1m) 67 Ga 78 h 150 1.25 mm Pb). to keep the surface dose level with in regulatory limits.0 h 800 6. Syringe shield (Exposure decreases 100 fold) ii. Table 8. For example. These materials are used to design the following protective devices: i. Lead pigs (dispensing system) iv. This shielding is in higher than the minimum required shielding.5 cm. Patients should be given instructions leaflet detailing contact with other people and appropriate action if clothing becomes contaminated.6 111 In 2. Usually tungsten or lead are used as shielding materials in nuclear medicine.0 131 I 8. But lead apron has limited value in nuclear medicine as it do not attenuate medium energy photons (140 keV). The dose rate from an unshielded vial containing 100 mCi (4 GBq) of 99mTc would be 800 μSv/ h at 30 cm.9 228 201 Tl 73 h 80 0. Suitable precautions are required to reduce staff radiation dose. The radiation levels from a medium size unshielded technetium generator having 500 mCi (18.8 d 80 2. 6. disposable gloves. Personnel Wear The personnel should wear laboratory coat. Patient who have received radionuclide injection should be kept in a separate areas in the department.5 m. The required minimum thickness of shielding is 1.0 d 40 0.3 cm lead shielding (9 HVL) is the minimum required to keep the radiation level at 15. A typical shielding used is 9.). in the case of Mo (HVL =7 mm lead) Syringe shielding is made up of 3 mm thick lead to reduce finger and body doses by about 200 times from syringe activities.4 99m Tc 6. Wearing a lead apron of 0. and 6 μSv / h at 1m respectively.3 . Leaded glass (Radio pharmaceutical preparation areas) iii.5 cm of lead.5 mm Pb (HVL =0. For example. The trauma imposed on the child and mother restricting contact should be weighed against the radiation risk. Several multiplication factors are used for obtaining children doses from the adult dose as follows: i.73 ii. Personnel Protection Patient Dose Reduction When using radionuclides for patient studies the following points will reduce dose to the staff: i. bladder wall dose of 43 mSv and whole body dose of 30 mSv respectively. For static imaging studies first three steps (i. Protective clothing (disposable plastic gloves. Most radionuclides used in nuclear medicine investigations are concentrated in breast milk. the patient radiation doses in nuclear medicine studies are much lower than the radiology investigations using X-rays. Child’s weight ÷ 70 kg iv. ii and iii) are used and for dynamic study last step (iv) is used. A diagnostic image in a reasonable time iii. Contamination Control Contamination control measures are designed to prevent radioactive material from coming into contact with personnel and prevent its spread to other work surfaces. divided by age +7 iii. Pediatric Exposure The injected activity depends upon the weight and age of the patient. Guidelines are given for a standard man on the radiopharmaceutical package. Hence either nuclear medicine investigations should be avoided or the mother is instructed to bottle feed after the investigation for a suitable period. Good counting statistics in laboratory tests ii. Acceptable radiation dose to the patient from the target organ and excretion path way iv. Child’s height ÷ 174 cm. Cost of expensive isotopes (123I. A neonate thyroid gland can receive a high radiation dose from these nuclides in mothers milk. However. For example. lab coats. Body surface area (BSA) ÷1. closed toed shoes) and handling precautions are the basic methods of contamination control. a urogram using iodine contrast may yield an ovarian dose of 30 mSv.111I). The personnel and work surfaces are routinely surveyed for contamination and areas should be classified as radioactive and non radioactive. Over 90 % of the Tc-99m activity appears in the breast milk over 24 h and breast feeding can continue after this term. The work surfaces where unsealed radioactive material is handled should be covered with plastic backed 229 . Child’s age +1. The contaminated areas are decontaminated followed by additional swipe tests. Label all radioactive containers with radionuclide name. Do not pipette radioactive materials by mouth. Handbags. For skin contamination. where as internal contamination can give significant radiation exposures. that can enhance internal absorption. The GM survey is repeated to confirm decontamination.g. wash with soap and warm water and any aggressive decontamination may create aberrations. To monitor the contamination control. No foodstuffs or drinks should be stored where radioactive sources are kept. Collimators of scintillation cameras should be covered with plastic to avoid contamination. Areas that are in twice the background level are said to be contaminated. Persons with an open wound should not work with radioisotope. Lab coats. iv. drinking. should not be brought inside the laboratory. smoking or applying of cosmetics should occur in areas where open sources may be present. key chains etc. vi. When it is contaminated or worn. it should be changed. vii. iii. v. Swipe tests (filter paper. Safety Work Practices that Can Reduce Internal Radia- tion Dose i. Xe-133 gas) should be stored in a 100% exhaust fume hood to prevent airborne contamination and subsequent inhalation. These swipe samples are counted in a NaI (Tl) gamma well counter. In the areas of radioactive waste and storage. No eating. and other protective clothing should not be taken home. handkerchives. activity and chemical form. to minimize internal contamination. All personnel should wash their hands after handling radioactive material (before eating or drinking). or cotton tipped swipes) are taken on weekly basis at various locations of the nuclear medicine department. Personnel should discard gloves in the radioactive waste dustbin after work and monitor their hands. Textbook of Radiological Safety absorbent paper. such as laboratory refrigerators. Personnel should wear laboratory coats and gloves when handling radioactive sources. aprons. Volatile radionuclides (e. a contamination monitor with GM type survey meter is used at the end of the day. shoes and clothing for contamination at periodic intervals. the radiation levels are higher and hence exposure rate meters (ion chamber) survey is carried out to detect high exposure rates. I-131. Gloves should be handled so as to avoid contamination of their inside surfaces. 230 . External contamination is not a health hazard. calibration date. alcohol wipes. ii. 10 for Tc-99m and I-31 respectively. Containers with sharp or broken edges should not be used for radioactive materials. Work with radioactive gases or other volatile materials should be performed in a ventilated fume hood. Work should be performed on absorbent pads to catch spills and prevent spattering of liquids. and patient’s name. of I-131 therapeutic require a written direcetive consisting the patient identity. Radioactive materials should be stored when they are not in use. If she is a mother. The recommended cessation of breast feeding periods are given the Table 8. until the radioactivity in the breast milk reduces to a safe level. Ensure that X-133 ventilation studies are performed in a room with negative pressure with respect to hall way (if the exhaust rate is higher than the supply rate. Work areas should be kept tidy. Pipettes and stirring rods should be placed in non porous trays or pans. x. xvii. These materials also should be stored in a hood. radiopharmaceutical. The patient’s identity must be verified by two ways (Name and social security number). xiii. Personnel Protection viii. xvi. xv.9 and 8. xiv. then air will flow from hall way to room). doorknobs. xix. Radioactive storage areas (hot labs) should not be used to store other materials. breast feeding is ruled out. In the case of women patient. and other items that could result in unsuspected contamination to personnel should be avoided.Hands should also be monitored before going to lunch or on breaks and before leaving at the end of the day. xi. by a pregnancy test. contaminated pads. radionuclide. Personnel should wash their hands after working with radioactive sources. xii. Spills or accidents should be reported to the radiological safety officer (RSO). Radioactive trash. Needless contamination of light switches. whether she is pregnant or not is to be ascertained. such as office supplies or linens. ix. activity and the rute of administration. and they should be checked for contamination by a monitor. Syringe containing a radiopharmaceutical must be labeled with radiopharmaceutical name and patient name. Activity >30 μCi. Women. 231 . and so forth should be disposed of promptly. Labeling and Identity The vial radiation shield containing radiopharmaceutical vial is labeled with radiopharmaceutical name. Discard all radioactive materials in the radioactive waste dustbin xviii. nursing the infants should be advised to discondinue breast feeding. radiopharmaceutical to mothers Activity Imaging Breast milk. toilet.1 x 10-7 Discontinue Treatment (ablation) PROTECTION IN RADIONUCLIDE THERAPY The treatment of thyroid cancer. and hyperthyroidism with I-131(8 days half life). The nursing staff should wear dosimeters.07 mSV / hr. radiopharmaceutical to mothers Activity Imaging Breast milk.1 x 10-7 Discontinue 100 mCi Thyroid cancer 4. bed. Patients meals are served by disposable meal trays. The radiation survey is made around the bedside.9: Cessation of breastfeeding after administration of TC-99m. If the total dose equivalent is >1mSv.2 x 10-1 17 hr 5 mCi Liver spleen scan 1. The visitors are instructed to wear disposable shoe covers and the visiting times are limited Patient with I-131 therapy may be discharged once the activity <33 mCi or dose rate at 1m <0.6 x 10-1 15 hr 15-25 mCi. Tc-kits All 8.1 x 10 -1 17 hr Table 8. MAA Lung perfusion 1. safe Cessation of breast level.MDP Bone scan 2. Textbook of Radiological Safety Table 8. mattress. After the discharge the room is completely surveyed and decontaminated. It has to be confirmed by swipe tests and GM survey. μCi/ml feeding 5 μCi Thyroid uptake 4. Hence before administration. I-131 is excreted through urine. safe Cessation of level. the patient may be discharged with instructions.2 x 10-1 10 hr 10-15 mCi.DTPA Renal scan 1. This is to minimize radiation exposure and contamination to other individuals. doorway and the neighboring room and the levels are posted for information along with instructions to nurses and visitors.1 x 10-7 Discontinue 33 mCi Out patient therapy 4. light switches. The radiation safety instructions that may be given to the patients are as follows: 232 . disposable shoe covers and gloves. Waste containers are placed in patients room to dispose meal trays and contaminated linens.2 x 10-2 24 hr 5-25 mCi.1 x 10-7 68 days 10 mCi Thyroid cancer scan 4.10: Cessation of breast feeding after administration of I-131. μCi /ml breast feeding 10 mCi Thyroid scan 8. Once it is administered. plastic backed absorbent paper is used to cover floor.2 x 10-2 24 hr 3-5 mCi. saliva and perspiration. require patient isolation. and telephone. As a result of this. Do not kiss anybody. iv. Particular discretion is required to ascertain the possibility 233 . ii. and they are independent of the imaging equipment. plates. Stay 3 feet away from other people. realizing that an administered radioactive material has been incorporated into her body. the patient may be even more apprehensive. Woman of Childbearing Age and Nuclear Medicine Examinations In women of childbearing age. x. Breastfeeding xi. the pregnant patient can be apprehensive after a procedure has been performed. vii. PREGNANCY AND RADIATION PROTECTION IN NUCLEAR MEDICINE As with diagnostic radiology procedures. all personnel clothing should be washed separately. the possibility of pregnancy and the justification for the examination should be considered. Double flesh the toilet for the first 2 days. and eating utensils immediately after use. Breast feeding must be discontinued. iii. Personnel Protection First 4 Days i. In contrast to diagnostic radiography examinations. Sleep in a separate bed. Avoid holding infants / children for long periods in a day. This is to avoid radiation exposure from patient thyroid to others. viii. Follow the physicians advise carefully. fetal doses in nuclear medicine depend predominantly upon administered activity. Next 3 Days ix. The ICRP-84 report recommended precautions to prevent or minimize irradiation of the fetus include the following: i. that it will be there for some time and that it potentially may cross the placenta to the fetus. The patient must be carefully interviewed to assess the likelihood of pregnancy. In the case of nuclear medicine. vi. as the urine contain large portion of activity. Use individual towels and wash clothes. Avoid sitting close to others for hours together. or use disposables. Contact with infants and pregnant women should be avoided. Wash cups. At the end of 2 days. v. more careful explanation to the patient and her husband or other appropriate persons may be needed to put the potential radiation risks into perspective. a pregnancy test may be indicated before proceeding. It is stopped for 12 hours after iodine labeled hippurates and all 99mTc compounds except labeled red blood cells. For example: If it is possible that you might be pregnant. and after 22Na. and a non-technetium or therapeutic radiopharmaceutical is being administered. In order to minimize the frequency of unintentional radiation exposures of the embryo or foetus. -phosphonates. The special conditions related to radioiodine therapy are discussed later. provided there are strong clinical justifications and effort 234 has been made to explore alternatives involving non-ionizing radiation. unless there is information that precludes pregnancy (e. and they may not mention a potential pregnancy until after the radiopharmaceutical has been administered. since many radiopharmaceuticals can be transferred to a baby via breast milk. questions arise about the advisability of becoming pregnant after a nuclear medicine examination or treatment. This is not usually a consideration except for radioiodine therapy or radiopharmaceuticals labeled with 59Fe (for metabolism studies) or 75Se (for adrenal imaging). ii. and ±DTPA. it is necessary to consider as pregnant any woman of reproductive age presenting herself for a nuclear medicine examination at a time when a menstrual period is overdue or missed. 67Ga. iii. it is recommended that pregnancy be avoided for 6 and 12 months respectively.g. Breastfeeding is usually stopped for 3 weeks after all 131I and 125I radiopharmaceuticals except labeled hippurate. Therefore. hysterectomy or tubal ligation). Textbook of Radiological Safety of pregnancy in an adolescent. before administering radiopharmaceuticals. As a result of the long physical half-lives of these radionuclides and their long residence times in the body. advisory notices should be posted at several places within the nuclear medicine department. Actions and Precautions that can Reduce Radiation Exposure to the Fetus Pregnancy need not be considered a contradiction for nuclear medicine procedures. and particularly at its reception area. and 201T1. Occasionally. Many laboratories also ask all females to indicate if they are breast- feeding. iv. and for at least 4 hours after the latter compounds. Many patients incorrectly assume that irradiation from a nuclear medicine examination begins when the gamma camera begins imaging. If the menstrual cycle is irregular. in particular diagnostic ones involving short lived radionuclides. . The ICRP has recommended that a woman not become pregnant until the potential fetal dose from remaining radionuclides is less than 1 mGy. Cessation of breastfeeding for at least some period is recommended for most nuclear medicine studies. notify the physician or technician before receiving any radioactive material. The physical.9-9. Occasionally.3 131 I Thyroid uptake1) 0.1 Gy / MBq for 131 I. RADIOIODINE THERAPY AND PREGNANCY Treatment of Pregnant Patients with Radionuclides As a rule.6-4. viz. Personnel Protection Since radionuclides in maternal tissues contribute to fetal dose.6-6.0-2.11: Fetal whole body dose from common nuclear medicine examinations in early pregnancy (Dose includes maternal and fetal self-dose contributions).4 3. the potential absorbed dose and risk to the foetus should be estimated and conveyed to the patient and the referring physician. This is feasible if the patient is not too sick and is able to remain still.7 99m Tc Red blood cell 930 3.4-0. and ICRP 80) Radiophar.6 1. Sparks. Radioiodine therapy is essentially contraindicated in patients who are known to be pregnant.55 0.11. Stabin.5-0.1 99m Tc Renal DTPA 750 5.1 99m Tc Thyroid scan (pertechnetate) 400 3.4-0.1-0.0 2. as well as from external irradiation from radioactivity in the mother’s organs and tissues. Irradiation of the fetus results from placental transfer and distribution of radiopharmaceuticals in the fetal tissues.3 0.9 11.2-4.6 0. Considerations may include terminating the pregnancy.0 1) Foetal thyroid doses are much higher than foetal whole body dose. 1997. a pregnant woman should not be treated with a radioactive substance unless the radionuclide therapy is required to save her life: in that extremely rare event.03-0.5 67 Ga Abscess / tumor 190 14-18 25 123 I Thyroid uptake1) 30 0. Radioiodine easily crosses the placenta and the fetal 235 . Procedure Administered Early Nine months maceutical activity (MBq) pregnancy (mGy) (mGy) 99m Tc Bone scan (phosphate) 750 4.5 99m Tc Liver colloid 300 0.8 99m Tc Lung perfusion (MAA) 200 0. 5-15 mGy / MBq for 123 I and 0. chemical. maternal hydration and frequent voiding can reduce the fetal dose after the administration of a number of radiopharmaceuticals.0 3.04 0.15 131 I Metastases imaging1) 40 2. the sequence of the examinations and choice of radiopharmaceutical can be adjusted to reduce radiation dose. Using smaller administered activities and longer imaging times can reduce the absorbed dose to the foetus.7 1. (Adapted from Russell. ICRP 53. Typical fetal doses from nuclear medicine examinations for common radiopharmaceuticals are presented in the following Table 8.6 0.5-1. et al.8 99m Tc Lung ventilation (aerosol) 40 0. and biological properties of the radiopharmaceuticals are the critical factors in possible placental transfer. Table 8. In women. it should be delayed until after delivery. the pregnancy is early and the major problem is fetal whole body dose due to gamma emissions from radioiodine in the maternal bladder. If this is not done the infant may become permanently hypothyroid or be at high risk for subsequent thyroid cancer. the whole body dose to the conceptus is in the range of 50±100 mGy/MBq of administered activity. is treated for thyroid carcinoma and is found to be pregnant after the administration of radioiodine. Twelve hours after radioiodine administration. In spite of the above. this intervention is not very effective. If radioiodine treatment of thyroid carcinoma is to be performed. If the conceptus is more than 8 weeks post conception (and the foetal thyroid may accumulate iodine) and the pregnancy is discovered within 12 hours of iodine administration. Thyroid cancers are relatively non-aggressive compared to most other cancers. As a result both surgical and radioiodine treatment are often delayed until after pregnancy. When a Family Member is Treated with Radioiodine Patients treated with radioiodine can be a significant radiation source to pregnant family members. Menstrual history is often not adequate to ensure that a patient is not pregnant. it will be surgery during the second or third trimester. thyroid carcinoma comprises over 80% of cancer of the head and neck diagnosed between the ages of 15 ± 45 years.5 meters from a patient until the radioactivity totally decays (about 10 . The dose to a family member staying at a distance 236 of 0. In most developed countries. it still happens that pregnant women are treated. the physician should also be aware that radioiodine is excreted in breast milk and breastfeeding should be stopped completely after a therapeutic dose. either because of false histories or because the pregnancy is at such an early stage that the pregnancy test is not yet positive. If this is done. who is not thought to be pregnant. if any therapy is to be performed during pregnancy. In general. This dose can be reduced by hydrating the patient and by encouraging frequent voiding. During pregnancy. Steps to be taken in Patients Found to be Pregnant after Administration of Radioiodine Therapy A major problem occurs when a female. giving the mother 60 ± 130 mg of stable potassium iodide (KI) will partially block the foetal thyroid and reduce thyroid dose. Textbook of Radiological Safety thyroid begins to accumulate iodine at about 10 weeks of gestational age. Most commonly. it is common practice to obtain a pregnancy test prior to high-dose 131I scanning or therapy for women of childbearing age unless there is a clear history of prior tubal ligation or hysterectomy precluding pregnancy. Risk to a Pregnant Woman. Radiopharma- ceuticals that are retained by the mother. e. Personnel Protection weeks) is about 1. be encouraged. . After the administration of such radiopharmaceuticals. acting as a reservoir. and are taken up in foetal tissues. increasing the potential for internal uptake. Moreover. but also iodide is volatile. Avoid of Pregnancy after Radionuclide Therapy Most female patients are advised not to become pregnant for at least 6 months after radiotherapy with radioiodine. Maternal Hydration In the case of radiopharmaceuticals that are rapidly eliminated by the maternal kidneys.8 mGy from a thyroid cancer patient. radiostrontium for calcium and radiocaesium for potassium) are less readily transferred. If the institution administers therapeutic activities of 131I for thyroid cancer. Some radiopharmaceuticals cross the placenta freely.g. Because the exposure from patients who have been administered radiopharmaceuticals is quite low. radioactive iodides. It is also based upon the fact the ICRP has recommended that enough radio- iodine be cleared to ensure that the unborn child does not receive a dose in excess of 1 mGy unless it is medically necessary for the health of the mother. Not only that there are higher exposures associated with the administration of 131I. 24. 237 maternal hydration and frequent voiding should. these patients must be careful not to transfer radioiodine contamination to family members by direct or indirect means. 89Sr.g. the International Basic Safety Standards require that “notification of pregnancy shall not be considered a reason to exclude a female worker from work”. is a major source of foetal irradiation.3 mGy from a hyperthyroid patient and 6. pregnancy should be avoided for 3. should be considered refraining from this particular part of the practice. This is not based upon potential heritable radiation effects. Also. In order to keep the dose to the foetus below 1 mGy. there is no radiological reason not to continue imaging procedures. STAFF PROTECTION Pregnant Staff and Continuation of Work For most diagnostic procedures. and 3 months respectively. Some analogues of natural metabolites (e. radiocolloids). There are occasional circumstances in which 32P. there would be no need for pregnant staff to take any additional precautions other than limiting their direct contact to as short as necessary. the urinary bladder. or 131I meta- iodobenzylguanidine are used for therapy.g. therefore. and (2) that another treatment with radioiodine is not going to be needed when the patient is pregnant. only act as external sources of irradiation to the fetus. and do not cross the placenta (e. where they irradiate the tissues. but rather upon the need to be sure (1) that the hyperthyroidism or cancer is controlled. If the scan is performed with 133Xe gas. in order to terminate the treatment with in the intended time. The position of the sources are retained in the same way through out the treatment time. in radiotherapy units. The choice of radiopharmaceuticals for the ventilation portion of the lung scan can also affect fetal dose.g. replacement of the decayed sources with fresh sources of higher activity is necessary and the frequency of replacement depends upon the half life of radioactive source used (e. there is very little fetal dose. These tests should be repeated periodically and their records are maintained in the form of log book. PERSONNEL SAFETY DURING SOURCE TRANSFER OPERATIONS OF TELETHERAPY AND HDR BRACHYTHERAPY UNITS Owing to the decay of the radiation sources. including sources and accessories. and while in the bladder it will contribute to fetal dose. 5 yrs. then the operator should watch the treatment. This will be absorbed and excreted via the kidneys. Textbook of Radiological Safety For those radiopharmaceuticals that have gastrointestinal excretion however. RADIOTHERAPY Teletherapy equipment or Brachytherapy equipment. These instruments are calibrated and maintained in good working condition. This has advantages in some situations. more attention is needed during the source transfer of the teletherapy units. In Brachytherapy the applicator / sources in the patient must be verified with the help of radiography or autoradiography. however. In routine operation. Appropriate equipments and accessories must be made available for performing dosimetry. the perfusion scan can be performed first. many laboratories will perform the ventilation scan first and then do the perfusion scan. Ignoring any of 238 the recommended procedures and steps may result in a serious radiation accident and elaborate and expensive management of the situation. simulation and quality assurance. administration of laxatives is only rarely helpful in reducing fetal dose. and if the result is normal. for cobalt-60). The activity of a teletherapy source is much higher that that in a remotely controlled after loading brachytherapy unit. shall not be used unless all the relevant quality assurance tests have been satisfactorily performed. If the treatment time is in the order of minutes. Sometimes. Therefore. treatment planning. A typical example of sequence is a ventilation perfusion lung scan ordered on a pregnant patient to exclude a pulmonary embolus. . one can also do ventilation scans using 99mTc-DTPA aerosol. The activity of these sources is dependent on the make and model of the therapy unit. a ventilation scan is not needed at all. the repair work of the unit’s head also demands source transfer operation. In the specific case of a suspected pulmonary embolus. Gynie and Multisource BEBIG. all over India. Table 8. Varisource iX Mumbai Flexitron M/s. Table 8. 80/100 Shinva FCC 8000 Cylindrical M/s. The decayed source is first removed from the unit and loaded into source flask. Eckert and Ziegler.Isodose Control.12: Teletherapy units Model of the unit Type of source drawer Local agents Theratron-780 Cylindrical M/s Kirloskar Theratronics 780C. Bengaluru ATC-C9 Capsule UB Electronics Instruments Ltd.. Pvt. The new sources loaded in drawers or capsules are transported in special source flasks designed for the particular make and model of the therapy unit. 780E.Chennai 239 . Varian Medical Systems India Pvt. Nucletron India Pvt.Tiruchirapalli.13: Brachytherapy units Model of the Unit Local agents Selectron LDR M/s. Alcyon Head @ Varian Medical India Pvt.Chennai Microselectron HDR Microselectron HDR Genie Gamma Med plus iX M/s. the source flask is used for removing the source from the unit and for reloading it into the therapy unit on completion of the repair work. During repair works (involving head of the unit) also. Indelelect Technologies Shinva FCC 8000 F Chennai Bhabhatron-II Cylindrical M/s Panacea Medical Technologies Pvt.Ltd. The source flask is used to carry out the source transfer operation. which is replaced during the source transfer operation. Ltd..13 gives the details about the remotely controlled brachytherapy units available in India.12 gives details about some of the teletherapy units available in the country and the type of source drawer of each mode.. Mumbai @ : Source is loaded in unit’s head. Personnel Protection Make and Models Different types and makes of teletherapy and brachytherapy units are installed and subsequently serviced by various manufacturers.. Table 8. Ltd. Ltd. New Delhi Phoenix Theratron-1000E Equinox. New source is then loaded into the unit. Table 8. Ltd. Parking rod required for pushing the stuck source drawer or shutter should always be available in the control room. 11. 10. After confirming the alignment between the source flask and unit head. 5. Also. In case the source transfer operation is to be carried out in the ON position (like in Philips or Picker units). Personnel monitoring badges. 2. After the transfer of the new source into the teletherapy unit. There are no hard and fast rules. Pocket dosimeters and Pocket alarm type radiation monitor should be used by all personnel involved in the operation. in case the unit is moved accidentally. It is the responsibility of serving company to ensure safe transport of the source flask loaded with new source either supplied by Board of Radiation and Isotope Technology (BRIT). Proper procedure should be adopted for the alignment of the source flask with the unit head. 9. family 240 members. 6. 3. Mumbai or imported and the return of the decayed source back to the supplier. proper locking device should be provided to prevent the movement of the system in case of power failure. Proper functioning of the unit. Non- standard gadgets which may delay the source transfer operation and may lead to radiation accidents should not be used. the source flask should be immobilized. treating oncologist and other team members should carefully discuss the decisions made. Textbook of Radiological Safety General Precautions 1. source transfer operation without dummy drawer should not be carried out. Necessary coupling devices should be used to facilitate proper alignment. all unnecessary materials around the flask should be removed. All the regulations for safe transport should be strictly followed. All the gadgets required for the source transfer operation as per the check list should be made available before undertaking the operation. 7. proper arrester or arresting plates should be employed to prevent the slipping of the source drawer. Proper arrester/s should be provided on the source flask after removing the lids so that source drawer does not slip down accidentally during the alignment process. 8. but the patient. 4. PREGNANCY AND RADIATION PROTECTION IN RADIOTHERAPY Special care needs to be taken when considering radiotherapy for patients during pregnancy. after loading of new source. Wherever dummy drawer is required in the source transfer operation (theratron and Siemen’s Model). should be checked with shutter open to minimum size and beam pointing opposite to maze wall. . 3. Consider modifications to the treatment plan that would reduce the radiation dose to the fetus (e. but important factors must be considered. include: 1. do not take portal localization films with open collimation and blocks removed.and load-bearing specifications of the treatment couch or other aspects of shielding support. Fetal assessment and monitoring. 8. Be present during initial treatment to assure that shielding is correctly placed. Monitor the fetal size and growth throughout the course of treatment and reassess fetal dose if necessary. ethical. Impact of delaying therapy. Complete all planning as though the patient were not pregnant. efficacy. Potential hormonal effects of pregnancy on the tumor. Legal. How and when the baby could be safely delivered. If possible use photon energies of less than 25 MV. The stage and aggressiveness of the tumor. On completion of treatment. 2. If the decision is made that radiotherapy is necessary. a very important factor in fetal dose is the distance from the edge of the radiation field. 3. 7. and moral issues. a shield may be constructed with 4-5 half-value layers of lead. Estimate dose to the fetus using phantom measurements. 2. 6. . Document the treatment plan and discuss it with the staff involved in patient set-up. The location of the tumor. Whether the pregnancy should be terminated. 9. it is important to calculate the dose to the fetus before the treatment is given. 11. Check the weight. as suggested by the ICRP. The most important considerations. Reduction of Fetal Dose When a Pregnant Patient Undergoes Radiotherapy The first consideration is if the treatment can be postponed until the fetus is at a later gestation age. When external radiotherapy is used for treatment of tumors at some distance from the fetus. radiation energy). If the foetus is near the treatment beam. The stage of pregnancy. Document the shielding (perhaps with a photograph). 8. changing field size. 5.g. Personnel Protection Pregnant Woman and Radiotherapy Pregnant patients can be treated with radiotherapies. and complications. The American Association of Physicists in Medicine (AAPM) recommends that the following points for consideration: 1. 6. Expected effects of maternal ill-health on the fetus. Various therapies and their length. 10. 4. 4. 7. document the total dose including the range 241 of dose to the fetus during therapy. 5. What are the possible effects on the fetus? There is no likely effect. Pregnant Patient with Cervical Carcinoma Who Needs Radiotherapy Treatment The patient diagnosed as cervical cancer may be treated with radiotherapy with external and Brachytherapy treatment. it is likely that pregnancy will be terminated. even the Japanese atomic bomb survivors. Avoid of Pregnancy after Receiving Radiotherapy for Breast Cancer Treatment The wait can be substantial and needs to be discussed with her radiation oncologist. varies significantly by country. However. The World Health Organization estimates that the worldwide incidence of inherited disease (ranging from severe to as trivial as an inconspicuous birthmark) is about 10%. Cervical cancer is often treated by surgery/radiotherapy (external beam radiotherapy and brachytherapy) and the absorbed doses required with both forms of radiotherapy will cause termination of pregnancy. Consider referring the patient to another institution if equipment and personnel are not available for reducing and estimating the fetal dose. If the tumor is infiltrative and is diagnosed late in pregnancy. most likely fetal death. Textbook of Radiological Safety 9. it is extremely unlikely that it would be related to the earlier radiation exposure. No data from humans show any statistically significant genetic effect in any population. If she is found to be pregnant unfortunately. it is not easy to extrapolate this data to humans. Illustration 1 A patient just finished four weeks of radiation treatment to the neck area for non-Hodgkin’s lymphoma. This is not primarily related to concerns about potential radiation effects. . so any effect on the offspring would be classed as genetic effect. This rate. Most radiation oncologists advise their patients not to become pregnant for 1-2 years after completion of therapy. which show that males are far more sensitive than females. or chemotherapy. Radiation exposure occurred before conception. Regardless of protective measures. There is very low risk of any effect on the unborn child. Carcinoma of the cervix is the most common malignancy associated with pregnancy. All estimates of genetic radiation risk come from studies of rodents. Cervical cancer complicates about one out of 1250 to 2200 pregnancies. In the unfortunate event that the 242 child is born with any genetic abnormality. surgery. an alternative is to delay treatment until the baby can be safely delivered. however. After one month. radiotherapy involving the pelvis of a pregnant female almost always results in severe consequences for the fetus. she got pregnant. but rather to considerations about the risk of relapse of the tumour that would require more radiation. the potential dose to the fetus is very low.14: Table 8. Other brachytherapy patients are kept in the hospital until the sources are removed. While these patients can occasionally be a source of radiation to a pregnant family member. and the patient is discharged from hospital with these in place. QA register (daily/quarterly/annually) 6. Source inventory register 10. Physicist to whom by If any /RSOsign 243 . Patient Treatment register 5. Calibration register 7. Personnel Protection Illustration 2 What is the risk to a foetus if a man who has had a radiation pellet inserted into his prostate for cancer treatment comes into close proximity with a pregnant woman? There is no danger involved. Prostate brachytherapy can be performed with permanent implantation of radioactive 103Pd or 125I seeds. Every machine should have a separate machine log book and the entries are made as follows in Table 8.14: Model log book Date defect Reported solutions Serviced Down time Instructions. Source movement register 11. the following log books are maintained 9. Source disposal register The number of logbook and type of entries varies with the machine and type of treatment. Patient case sheet 2. RECORDS Treatment records must be maintained to facilitate unambiguous and correct treatment follow up. The short range of the emissions from these radionuclides is the reason that the patient can be discharged and is the reason that these patients pose no danger to pregnant family members. Patient planning (TPS) register 4. irrespective of the type of brachytherapy. Machine log book (for each machine) In brachytherapy also all the above records and log books are required. Patient simulation register 3. Radiation survey register 8. 1. In teletherapy the following records and log books are required. In addition. Europian commission. Cundiff J. Oxford 1991. Pergamon Press. ICRP Publication 53. 1. Stovall M. 2. International commission on radiological protection. 36. NRPB-W14. Doses to Patient from Medical X Ray Examinations in the UK: 2000 review. Textbook of Radiological Safety BIBLIOGRAPHY 1. Pregnancy and Medical Radiation. ICRP Publication 93. European Guidelines on Quality Criteria for Diagnostic Radiographic Images in Paediatrics. 5. Addendum to ICRP 53. Palta JR. Managing Patient Dose in Digital Radiology. Phys. Radiation Dose to Patients from Radiopharmaceuticals. Sparks RB. Pregnancy and Medical Radiation. Oxford 1988. Stabin MG.73:756-69. Annals of the ICRP. International commission on radiological protection. Chilton 2002. 7. Pergamon Press. Pergamon Press. Russell JR. International commission on radiological protection. ICRP Publication 80. Oxford 2000. Health Phys 1997. 10. EUR-16261. ICRP Publication 84. National radiological protection board. Luxembourg 1996. Med. et al. Wagner LK. International commission on radiological protection. 3. Radiation Dose to Patients from Radiopharmaceuticals. 244 .22(1):63-82. Pergamon Press. Oxford and New York 2004. Pergamon Press. International commission on radiological protection. 9. Novack DH. Oxford 1998. 6. Oxford and New York 2000. 1990 Recommendations of the ICRP. Pergamon Press. Blackwell CR. Publication 60. International commission on radiological protection. 1995. Foetal dose from radiotherapy with photon beams: Report of AAPM Radiation Therapy Committee Task Group No. Radiation absorbed dose to the embryo/ foetus from radiopharmaceuticals. 4. 8. Publication 84. . Limiting the amount of radioactive material in a package. These requirements must ensure the safety of persons. 1. property and the environment against radiological hazards involved in transport. Each package of gross weight exceeding 30 kg must have its gross weight legibly and durably marked on the outside of the packaging 7. The segregation distance is such that. and 3. There is a need for certain safety requirements during such transports. To minimize the hazards during transport of radioactive materials and to ensure safe transport of radioactive materials several procedures are adopted. 5.1mSv per consignment of such film. Limiting the radiation level on the surface of the package and at a distance of 1 meter from the surface of the package. depending on the ability of the package to withstand both normal and accidental conditions encountered during transport. 2. that are specified. The labels must be fixed on two opposite sides of the outside of a package or on the outside of all four sides of a freight container or tank. 8. 4. Large freight containers carrying packages other than excepted packages. Transport includes any operation incidental to the whole course of carriage. Segregating such packages from passenger areas and undeveloped photographic films. unloading and storage in transit. it should limit the exposure of undeveloped photographic film to 0. 6. The Types of package must be specified and the quantity of radioactive material in a package must not exceed the activity limits specified by the competent authority. which include. Each consignment of radioactive material is accompanied with declaration document as specified. Chapter 9 Transport of Radioactive Materials INTRODUCTION Radioactive materials are transported in a variety of types of packages. 9. such as loading. Packages must be designed to confirm the category and Transport index in accordance with the conditions and requirements. and tanks must bear four placards. The competent authority should be informed within 24 hours. AERB for permission and advice. Excepted packages d. other than special forms of radioactive material permitted under provisions of the Type A package. A2 is the maximum activity of radioactive material. The values of A1 and A2 of important clinical radionuclides are given in the Table 9. The sealed capsule should be so constructed that it can be opened only by destroying the capsule. TYPES OF PACKAGES Radioactive packages are classified into five types depending on total activity in a package. Type A b.1 (AERB safety code SC/TR-1. The package types are. Special radioactive material should (i) have at least one dimension not less than 5 246 mm. the doses to persons engaged in transport and other persons are as low as reasonably achievable. a. The main objective of the above code are that. the local police should be informed. during such transport.1986). to initiate steps to cordon off the area. and whether the material is fissile or not. SC/TR-3. Type A packages must not contain activities greater than A1 for special form radioactive material or A2 for all other radioactive material. the consigner should approach the Radiological safety division. shielding integrity of the packaging and the quantity of radioactive material determine the type of the package. Radioactive materials should be properly packed prior to transport and should be accompanied by appropriate transport certificates. A1 is the maximum activity of special form radioactive material permitted under provisions of the type A package. Type A Packages Type A packages are required to withstand the normal conditions of transport without loss or dispersal of their contents or loss of adequate shielding integrity. and SG/TR-3 for transport of radioactive materials. Prior to undertaking the transport of radioactive material. Type B c. Industrial packages e. The total activity of radioactive material in Type A package is limited. The Atomic Energy Regulatory Board (AERB) has issued certain guidelines in the form of codes SC/TR-1. . In case of emergency. specific activity of the material. Fissile packages. The special form of radioactive material means either an indispersible solid radioactive material or an ordinarily unbreakable metallic sealed capsule containing the radioactive material. and (ii)comply with the prescribed test requirements. Sturdiness. Textbook of Radiological Safety 10. Radioactive materials in quantities greater than those allowed in Type A packages are shipped in Type B packages. The design and shipment of Type B (U) package is subject to multilateral approval (country of origin and the country through which it is transported). as specified in their certificates of approval.4 10 Cs-137 2 50 0.1 2 Tc-99m 8 200 8 200 I-125 20 500 2 50 Type B Packages Type B packages are designed to withstand both normal and accidental conditions of transport.3 8 0.5 10 P-32 0.1: A1 and A2 values for clinical radionuclides Radionuclide A1 (TBq) A1 (Ci) A2 (TBq) A2 (Ci) Co-60 0.2 5 0. Type B packages are divided into two basic categories namely Type B(U) and Type B(M).5 10 Ir-192 1 20 0.4 10 0. Type B(M) packages do not meet all the requirements applicable to Type B(U) packages. they must incorporate alternative design features and operational controls must be instituted so as to achieve the same level of safety as for Type B(U).The type B(U) packages meet the most stringent requirements. An excepted package must not contain activities greater than A1 and A2 values of the radionuclides. Excepted Packages Excepted package means a packaging containing excepted quantities of radioactive material that is designed to meet the general requirements for all packaging and packages. the total activity in each package must not exceed one tenth of the above relevant limit specified. For transport by post. it is considered that safety is entirely built in to these packages. Transport of Radioactive Materials Table 9. The design of this package is subject to the approval by the competent authority of the country of origin.5 10 I-131 3 80 0.3 8 Ra-226 0. however. These packages are permitted to contain small quantities of radioactive materials and are excepted from various specific packaging and labeling requirements.3 8 2 × 10-2 5 × 10-1 Sr-90 0. Type B packages must not contain (i) activities greater than those authorized for the package design (ii) radionuclides different from those authorized for the packages design or (iii) contents in a form. 247 . or a physical or chemical state different from those authorized for the package design. The design of the packages are subject to the approval of the competent authority. 248 . SCO means a solid object which is not itself radioactive but which has radioactive material distributed on its surfaces. are subjected to multilateral approval. package design features and by controlling the number of packages to be carried on a single conveyance or to be stored together in transit. 1-10 and more than 10. LSA-II and LSA-III. The LSA has three groups namely LSA-I. All packages containing fissile material must comply with the applicable activity limits specified in the safety code. plutonium-239. Criticality safety in transport of fissile material is ensured by limiting the quantity and geometric configuration of the fissile material. different from those authorized for the package design. If the radiation level is measured in mSv /h. SCO has two groups namely SCO-I and SCO-II. or in a spatial arrangement. Packaging containing fissile material must not contain (i) a mass of fissile material greater than that authorized for the package design (ii) any radionuclide or fissile material different those authorized for the package design or (iii) contents in a form or physical or chemical state. Fissile Packages Fissile material means uranium-233.to arrive mrem /h. uranium-235. The packages containing fissile materials. TRANSPORT INDEX The Transport index (TI) of a package is the number expressing the maximum radiation level in mrem /h at 1m from the external surface of the package. External shielding materials surrounding the LSA materials must not be considered in determining the estimated average specific activity. or radioactive material for which limits of estimated average specific activity apply. as specified in their certificates of approval. plutonium-241 or any combination of these nuclides. which may be LSA. plutonium-238. it should be multiplied by 100. Type A or Type B. LSA material means radioactive material which by its nature has a limited specific activity. Textbook of Radiological Safety Industrial Packages The total activity in a single package of low specific activity (LSA) material or in a single package of surface contaminated object (SCO) must be so restricted that the external radiation level at 3 m from the unfinished material or object or collection of objects does not exceed 10 mSv/h and the activity in a single package must also be so restricted that the activity limits for a conveyance specified by the competent authority. SCO. The values of TI are 0. Packages with liquid radioactive material.005 mSv/h or 0. vibration etc. and (iii) category III-Yellow. The package should be capable of withstanding the effects of acceleration. The external surface of the package should be free from protruding features and can easily decontaminated.005 mSv/h. and with radioactive contents. The packages must be so designed in relation to its mass. All valves through which the radioactive contents could otherwise escape must be protected against unauthorized operation. but not more than 2 mSv or 200 mrem/h. The lifting attachments on the package should not fail when used in the indented manner.5 mSv/h.5 mSv/h or 50 mrem/h. . Packages to be transported by air. 4. 8. The Transport index is zero.5 mrem/h. (ii) category II-yellow. but not more than 1. transported by air. 6. should with stand ambient temperatures ranging from – 40°C to + 55°C 9. 7. 5. volume and shape that. The outer layer of the package must be designed as to prevent the collection and the retention of water. The Transport index is more than zero. Transport of Radioactive Materials Categories There are three categories of packages namely (i) category I-White. Category III-Yellow The maximum radiation level at any point on the external surface of the package should not be more than 0. PACKAGING AND PACKAGE REQUIREMENTS The package should satisfy the following general and specific requirements before they are used for actual transport. it could be easily and safely handled and transported. Category II-Yellow The maximum radiation level at any point on the external surface of the package should be more than 0. but not more than 0. The material of the packaging and the components must be physically and chemically compatible with one another. 3. but not more than 10. 2. General Requirements 1. The Transport index is more than 1. during transport. must with 249 stand an internal pressure of not less than 95 kPa. Category I-white The maximum radiation level at any point on the external surface of the package should not be more than 0. it is provided with sufficient absorbent material to absorb twice the volume of the liquid contents. The package containment system must retain its radioactive contents under a reduction of ambient pressure to 25 kPa. dynamic effects and filling dynamics. 2.2 m for packages weighing up to 5000 kg. suitable assessment must be made to assure that the requirements of the packages are fulfilled in conformance with the performance and acceptance standards. 4. Free Drop Test The specimen must drop on to the target so as to suffer maximum damage in respect of the safety features to be tested. When the packages are subjected to specified tests. These tests will demonstrate the ability of the package to withstand normal conditions of transport. 5. The height of drop measured from the lowest point of the specimen to the upper surface of the target must be not less than 1. Water Spray Test The specimen must be subjected to a water test that simulate exposure to rainfall of approximately 5 cm per hour for at least one hour. it would prevent (i)loss or dispersal of the radioactive material. 6. The design of the package must take into account temperatures ranging from 40-75°C. for the components of the packaging. 8. Any tie-down facility on the package should withstand both normal and accidental conditions. The containment system is securely closed by a positive fastening device. It will prevent unintentional release of radioactivity. 9. and (ii) loss of shielding integrity. it should accommodate variations in the temperature of the contents. After the specimen is subjected to tests. The outside of the package must incorporate a seal. and (iv) penetration test. 7. The design. It can not be opened unintentionally. If the packages carries liquid radioactive material. which may result >20% radiation level on the external surface of the package. 250 . fabrication and manufacturing techniques must be in accordance with national and international standards. to serve as proof against tamper. 3. Test for Type A Package The Type A package tests are (i) water spray test. Textbook of Radiological Safety Additional Requirements for Type A Packages 1. 10. (ii) free drop test. The smallest overall external dimension of the packaging must not be less than 10 cm. (iii) stacking test. If the liquid volume is less than 50 ml. the specimen must be dropped from 1 m. Mechanical Test This consists of three different drop tests. For drop I. 3. These tests will demonstrate the ability of the package to withstand accident conditions in transport. it would restrict the accumulated loss of radioactive contents in a period of one week to not more than 10 × A2 for Krypton-85 and not more than A2 for all other radionuclides. The height of drop of the bar must be 1m. The package must withstand heat generated within the package. suitable assessment must be made to assure that the requirements of the packages are fulfilled in conformance with the performance and acceptance standards. (ii) lessen the efficiency of the packing. that if it were subjected to the prescribed tests it would retain sufficient shielding to ensure that the radiation level at 1 m from the surface of the package would not exceed 10 mSv/h with the maximum radioactive contents which the package is designed to carry. so as to suffer the 251 maximum damage onto a bar rigidly mounted perpendicularly on the . A bar of 3. The package should meet the requirements of general requirements 1-8 and that of Type A package (1-10). Penetration Test The specimen is placed on a rigid flat horizontal surface. The packaging is so designed. For drop II. Additional Requirements for Type B Packages 1. 5. compression test and penetration test the loss of radioactive contents should be less than A2 × 10-6 per hour. Test for Type B Package The test for Type B packages are (i) mechanical test. free drop test. If the package is subjected to mechanical test. and (iii) accelerate corrosion in combination with moisture. 4. thermal test and water immersion test. 2. geometrical form or the physical state of the radioactive contents. Transport of Radioactive Materials Stacking Test The specimen must be subjected to a compressive load equivalent of 5 times the mass of the actual package for a period of 24 hours.2 cm diameter with a hemispherical end and a mass of 6 kg must be dropped and directed to fall. the specimen must be dropped from 9 m onto the target so as to suffer the maximum damage. If it were subjected to water spray test. (ii) thermal test and (iii) water immersion test. with its horizontal axis vertical. After the specimen is subjected to tests. so that the heat should not (i) alter the arrangement. on to the centre of the weakest part of the specimen. by keeping the packages as far away as possible. Two or more persons should be employed for handling the packages up to 100 kg.1mGy (10 mR). The mass must consist of a solid mild steel plate 1m by 1m and must fall in a horizontal altitude. The number of packages stored in an area should be restricted to ensure that the sum of the transport indexes of the packages stored in the area does not exceed 50. The bar must be a solid mild steel of circular section (15 ± 0. Thermal Test The specimen must be subjected to a fuel source (hydrocarbon /air fire). During manual handling. during the entire duration of the transport including 252 storage in transit. Water Immersion Test The specimen must be immersed under a head of water of at least 15 m for a period of not less than 8 hours in the altitude which will lead to a maximum damage. and must not extend more than 3 m.9 and average flame temperature of 800°C for a period of 30 minutes. it must be handled only by mechanical means. if the weight is > 100 kg. having a emissivity coefficient of 0. Textbook of Radiological Safety target. Packages weighing not more than 30 kg. Packages of radioactive materials should be kept segregated from areas routinely occupied by passengers and public. 3. . an external gauge pressure of at least 150 kPa must be considered to meet these conditions. They should also be so separated from underdeveloped X-ray and photographic films or plates so that these are not exposed to more than 0. The specimen must be positioned 1m above the surface of the fuel source. is provided with manual handling facility. 2. After the thermal test. beyond the external surface of the specimen. For drop III. Radioactive consignments should not be stored together with other dangerous goods (explosives. Package Handling Packages weighing <5 kg are not provided with handling facilities. operations should be completed quickly. If the weight of the package is not known. For demonstration purposes. a 500 kg mass is dropped from 9 m height onto the specimen.5 cm) in diameter and 20 cm long. the specimen must not be cooled artificially and any combustion materials of the specimen must be allowed to proceed naturally. Mechanical handling devices (crane. Storage in Transit Requirements 1.) should be employed to handle the packages. 4. The fuel source must extend horizontally at least 1m. inflammables etc). and one can hold them with hands. chain pulley block etc. it should be forwarded for transport as soon as possible. 6. Package Radiation Levels Radiation levels under normal transport conditions are limited so that maximum radiation level at the package surface should not be greater than 2 mSv/h (200 mR/h) and the maximum radiation level at 1m from the surface should not be greater than 0. The maximum radiation levels on the outer surface of the package and at a distance of 1m from the surface should be measured (mSv/h) by using a working radiation survey meter and recorded. When the consignment is brought for booking. If the package is damaged. and inform the competent authority. The container should be loaded in an outer container such as wooden or metallic box. 2. 5. 3. so that the source is not released during the transport. 253 . 7. It should be ensured that the outer container deployed is in a good condition and is provided with locking facility and strong lifting handles. relevant to their work. The lid of the container should be closed.1 mSv/h (10mR/h). An unclaimed or damaged package should not be auctioned or otherwise disposed off. isolate it by cordoning about 5 m around it. Transport of Radioactive Materials 5. Persons working in the storage area should spend minimum possible time in the vicinity of the packages. 4. The outer container should be locked and tied with crossed metal straps and sealed. The measured value is multiplied by 100. Alternatively the original container in which the fresh source was received can be used. provided if it is in good condition. 9. The source should be loaded in the container properly and carefully. 7. do not touch the package. to get the appropriate TI. The source should be transported only in an approved transport container. This will be useful to find the correct transport index (TI). 8. 6. It is provided with spacers within for preventing movement of the shielded container inside during transport. then only it is called transport package. MARKING OF THE PACKAGE Write or inscribe the following information durably. PREPARATION OF THE PACKAGE FOR TRANSPORT 1. The packages must be delivered to the consignee or his authorized representative only. clearly and legibly on the outer side of the package. The source should be secured within the shielded container by means of appropriate locking mechanisms incorporated in the design of the shielded container. Textbook of Radiological Safety 1. Addresses of the CONSIGNOR and the CONSIGNEE. 2. Type of package (e.g. Type A/Type B etc.). 3. UNITED NATIONS NUMBER (UN NO.), and the PROPPER SHIPPING NAME (please refer Table 11.3). 4. Gross weight of the package if it exceeds 30 kg for domestic transport and 50 kg for international transport. 5. Competant authority (i) identification mark allocated to that design and (ii) serial number to identify each package, if it is a Type B(U)/B(M) package. 6. In the case of Type B(U) or B(M), the outer surface should have the trefoil symbol (Fig. 9.1), which must be marked by embossing, stamping or other means resistant to the effects of fire and water. Fig. 9.1: The trefoil symbol LABELING OF THE PACKAGE Appropriate labels indicating the category of the package should be affixed on two opposite sides on the exterior of each package. In the case of a tank or freight container it should be on the outside of all four sides. Each label should be completed with the information required, i.e. with the content, activity and transport index. The criteria for determination of the category of the package are given in the Table 9.2 below: Table 9.2: Category of package, radiation level and transport index Category Maximum radiation level at the external Transport Index surface of the package, mSv/h, (mrem /h) I WHITE 0.005 (0.5) 0 II YELLOW 0.5 (50) 1 254 III YELLOW 2.0 (200) 10 Transport of Radioactive Materials Both the limits should be satisfied for a package to belong to a specified category. If either of the limits is exceeded, the package would belong to the next higher category. CAUTION: If either the radiation level on the surface of the package is more than 2.0 mSv/h or Transport Index is more than 10, the package should not be forwarded for transportation without prior permission of the competent authority. The Category I WHITE label background color must be white, the color of the trefoil and the printing must be black, and the color of the category bar must be red (Fig. 9.2). Fig. 9.2: Category I WHITE label Fig. 9.3: Category II YELLOW label (For color version see plate 3) (For color version see plate 3) In the case of Category II YELLOW label, the background color of the upper half of the label must be yellow and the lower half white, the color of the trefoil and the printing must be black, and the color of the category bar must be red (Fig. 9.3). In the case of Category III YELLOW label, the background color of the upper half of the label must be yellow and the lower half white, the color of the trefoil and the printing must be black, and the color of the category bar must be red Fig. 9.4: Category III YELLOW label (For color version see plate 4) 255 (Fig. 9.4). Textbook of Radiological Safety PLACARDS Large freight containers carrying packages other than excepted packages, and tanks must bear four placards as specified in Fig. 9.5. These placards must be affixed in a vertical orientation to each side wall and each end wall of the freight container or tank. Any placards which do not relate to the contents must be removed. Instead of using a label and a placard, it is permitted as an alternative to use enlarged labels, with minimum dimension of 25 cm. Fig. 9.5: Placard, the minimum dimensions is 25 cm. The figure 7 must not be less than 25 mm height. Background colour of the upper half must be yellow and the lower half is white, trefoil and the printing must be black (For color version see plate 4) If the freight container is packed with radioactive material comprised of a single United Nations commodity, the appropriate United Nations number (Table 9.3) for the consignment must also be displayed, in black digits not less than 65 mm height, either in the lower half of the above placards or in the placard shown in Fig. 9.6. Fig. 9.6: Placard for separate display of united nations number. The background color must be orange and border and the united nations number must be black. 256 The **** denote the space for UN number of radioactive material (For color version see plate 4) Transport of Radioactive Materials Table 9.3: United nations number and proper shipping name UN No. Proper shipping name and description 2910 Radioactive material excepted package-Limited quantity of material 2911 Radioactive material excepted package-Instruments or articles 2909 Radioactive material excepted package-Articles manufactured from natural Uranium or depleted Uranium or Natural Thorium. 2908 Radioactive material excepted package-Empty packaging 2912 Radioactive material, Low specific activity (LSA-I) 3321 Radioactive material, Low specific activity (LSA-II). 3322 Radioactive material, Low specific activity (LSA-III) 2913 Radioactive material, Surface contaminated objects (SCO-I or SCO-II). 2915 Radioactive material Type A package, non special form. 3332 Radioactive material Type A package, special form. 2916 Radioactive material Type B(U) package. 2917 Radioactive material Type B(M) package. BOOKING, STORAGE, TRANSPORT AND DELIVERY OF PACKAGE The package should not be transported as a personal luggage in a bus or in a shared Taxi or in the passenger compartment of a train or in the passenger cabin of an aircraft. It is always booked as an item of cargo. The package should not be dispatched by post. The package is declared as a radioactive consignment in the transport documents. For road transport, the consigner shall declare the consignment by its proper shipping name. The package is provided with transport documents, which include (i) Consigner’s declaration, (ii) TREM card (Transport emergency card), (iii) Instructions to the carrier and (iv) Instructions about emergency measures in case of transport incidents. The key of the lock should be sent along with the transport documents to the CONSIGNEE. The package should not be dispatched with out prior permission of the COMPETENT AUTHORITY. The CONSIGNEE should be informed before dispatching the package and ensured that the CONSIGNEE is prepared to receive the consignment. The CARRIER is provided with documents entitled “INSTRUCTIONS TO THE CARRIER”, while booking the package for transport. The CONSIGNOR, CONSIGNEE and CARRIER should contact the competent authority immediately in the event of : a. Any untoward incident /accident during transport b. Non delivery of the package to the destination within the normal period. It should be ensured that the CONSIGNEE has received the consignment or not and the same is informed to the competent authority. A Check list should be filled to ensure that all the requirements for safe transport of radioactive material are complied with. 257 Textbook of Radiological Safety CONSIGNOR’S DECLARATION This is to certify that the package containing radioactive material as identified by the following details is safe for transport by rail, road, sea or air. Package forwarded by (consignor) Package addressed to (consignee) Proper shipping name Radioactive material ————— package, Non fissile UN class of dangerous goods 7 United Nations No. UN NO. Subsidiary risk Nil Name of the radioactive material Quantity/Activity of radioactive material —————RMM on ———-—— Packages details Dimensions of package Weight of the package Type of package* Radiation level on the surface of the package in mSv/h Transport index of the package Category of the package *In the case of Type B(U)/(M) package, competent authority identification number should also be given. I hereby declare that the contents of this consignment are fully and accurately described above by the proper shipping name and are classified, packed, marked and labeled and are in all respects in proper condition for transport according to the AERB Safety code, AERB/SC/TR-1,currently in force. Date: Signature: Name and Address: 258 Transport of Radioactive Materials TREMCARD Cargo In-dispersible radioactive material Nature of Hazard Radioactive material, Potential external exposure Emergency action 1. Inspect the package visually. If it is intact, ensure onward journey in the same or another vehicle. 2. In case of fire, fight from a distance 3. If the package appears to be damaged cordon a distance of 3 m around the package. 4. Obtain the names and addresses of persons who might have been exposed to radiation and convey the particulars to the Head, AERB and to the Head, RP and AD, BARC, Mumbai. Contact telephone a. Contact the consignor at the address given on the numbers for advice and package assistance b. Chairman, Crises Management Group, DAE, Mumbai-400001, Tel : 022 22023978, 22830441, FAX: 022 228304441 c. Head, Radiological Safety Division, AERB, Niyamak Bhavan, Anushatinagar, Mumbai-400 094, Tel:022 25990655, FAX:022 25990650 d. Head, Radiological Physics and Advisory division, BARC, CT and CRS, Anushaktinagar, Mumbai- 400094, Tel:022 25519209, FAX: 022 25519209 Telegram REGATOM,CHEMBUR or HEAD,RP and AD, BARC- CHEMBUR FAX 022 25583230 (AERB),022 255055151(BARC) 259 Mumbai-400094 and such measures as recommended in this regard by HEAD. it should be ensured that the package is delivered to the consignee to whom it is indeed addressed. 2. 8. 7. At the destination. i. Further the total number of packages staked in a storage area should be so limited that in a given stack the above limit of 50 of the sum of transport indexes is not exceeded and such stacks containing radioactive consignments are separated by at least 6 meters. it should not be auctioned or otherwise disposed of. The matter should be brought to the notice of the consigner and Head. Suitable mechanical means should be deployed for handling packages weighing more than 30 kg. 5. the entire conveyance is for the proposed transport of radioactive material then (a) there should not be any intermediate loading and unloading operations of other goods. Textbook of Radiological Safety INFORMATION TO CARRIERS 1. 260 . The package should be transported by the most direct route. Persons should not be allowed to sit on the package or spend more time than the necessary time in the vicinity of the package. The package should not be transported along with other dangerous good such as explosives and inflammables. except in case of executive use. 9. Mumbai. AERB. 11. The package should be kept segregated from spaces occupied by passengers and public. If the package is not claimed by the consignee at the destination. 10. then the total number of packages loaded in a single vehicle should not be so restricted that the sum of the transport indexes of the packages does not exceed 50. The package should not be transported/stored together with photosensitive films/plates. (b) Nothing other than the intended radioactive material along with its accessories should be carried in this vehicle. Anushaktinagar. the instructions specified in the TREMCARD should be implemented. If several packages containing radioactive material are to be transported. 12. If the shipment is under explosive use. One copy of the TREMCARD should be carried in the vehicle carrying the radioactive cargo. If the package(s) get (s) involved in an accident or get (s) damaged during transport. Niyamakbhavan. 4. Package should be handled carefully. 6. 3. should be duly implemented.e. RSD. Intermediate off-loading and reloading of the package should be avoided. AERB. marking and labelling a package to transport radioactive material Type of the package: Type A /Type B (U)/Type B (M)/ other (please specify) If Type B(U) or Type B(M). Yes/No 3. give the Competent Authority Identification No. Whether the source is locked/arrested in its shielded position. Yes/No 5. address and telephone number of consignor (sender) and consignee (receiver). Yes/No 2. Whether the package is properly locked and sealed with crossed steel strips. _________ Preparation of the package 1. Yes/No 3. and the nuts/bolts are properly tightened. Yes/No Markings of the package 1. Yes/No 2. Whether all the nuts and bolts meant for fastening the shielding are properly in place. secured and tightened. Whether the Gross weight of the package is marked on it. Whether the proper shipping name of the radioactive material is marked on the package. if the weight exceeds 30 kg. etc. Transport of Radioactive Materials Annexure-I Check list for preparing. Yes/No 4. Yes/No 6. Whether the package is marked on the out side with name. Yes/No 261 . Whether the outer box (package) is properly closed with the help of fasteners/ bolts. steel straps etc. address and telephone number of consignor (sender) and consignee (receiver). Whether it was confirmed with radiation survey meter that the radiation source is in its proper storage place in the shielded container/source housing/ radiography camera. Whether the shielded container inside the package is marked with name. Yes/No 4. Whether the shielded container is properly immobilized in the outer container/ box (package) with the help of wooden spacers. Whether the carrier is informed that the package should not be carried in the passenger compartment of a train. Yes/No 7. Yes/No 6. Yes/No 3. Whether a copy of “instructions to the carrier” is provided to the carrier and the carrier is properly informed regarding the radioactive nature of the consignment and the hazards associated with it. etc. Whether the Consignor’s declaration along with particulars of the consignment are provided in proper format. Yes/No 3. Yes/No 2. Yes/No Labeling 1. an aircraft or passenger cabin of a ship or in a passenger bus or a shared taxi or any shared rented vehicle. Yes/No 2. Yes/No 262 . Whether the proper United Nation Number is marked on the package. Textbook of Radiological Safety 5. Whether all the markings made on the package are legible and durable. Whether the carrier is informed about the care to be taken during handling and carriage of the package in trans-shipments. Yes/No 4. Yes/No 2. Whether the copy of “Emergency instructions in writing” is provided to the driver of the vehicle. Yes/No Prior to actual transport of the package 1. Whether the package is labeled with two numbers of selected category labels affixed on two opposite sides of the package. Whether the TREMCARD is provided to the driver of the vehicle and whether it forms a part of the Transport Document. Whether label of proper category is selected based on the radiation. Yes/No Transport documents 1. Whether these labels are properly filled-in with respect to (a) Name of Radio nuclide (b) Activity in becquerel (c) Transport Index. Whether the Type of package is marked on it. Whether the consent of the consignee is obtained before dispatching the package. Yes/No 5. Yes/No Consignor’s Signature: Name and address Date: Seal. Whether the carrier is informed that the package should be immobilized during the transport. Transport of Radioactive Materials 3. Yes/No 4. 263 . Whether carrier is informed about the proper stowage of the package in the vehicle during the transport. save life. in addition. Nature of Hazard: The hazard associated with radioactive consignment is exposure to radiation. 4. • Two pairs of rubber shoes • Two pairs of latex gloves • Coveralls. If any of the 264 packages which are damaged in the accident was containing radioactive material .6) 1. It is such a package which is loaded in the vehicle. If the content is in dispersible form. Such exposure may be external and/or internal in nature. the potential for internal and some times. Rescue the injured. namely. Textbook of Radiological Safety Annexure-II Instructions in writing regarding Practical Measures for Transport Incidents Involving Radioactive Cargo (AERB/RSD/TRANSPORT EMERGENCY/REV. 2. then the package may be damaged through the loss of shielding or release of the contents may not occur. 2 numbers • Big empty polythene bags: 6 numbers • Big (3 m x 3m) polythene sheets • One kg of cotton wool. in the unlikely event of a severe accident. If the radioactive content is an in dispersible solid or capsule. A Type B package is designed to withstand severe accidents Only those packagings whose design and specifications have been duly approved by Atomic Energy Regulatory Board (AERB) for Type B(U)/(M) and registered in AERB for industrial and Type A package. It is unlikely that in a transport accident involving the commonly deployed small Type A and Type B(U)/(M) packages any significant injury to the rescuer will result from radiation. don’t panic. Essentially there are two types of packages. • The protective equipments include. If life is at stake. Type A and Type (B)U/(M). 3. the hazard is likely to be external. If the vehicle does not carry any package containing dispersible radioactive material the protective equipment would not be required from radiation safely standpoint. Emergency action and first aid: If an accident occurs. If a Type A package is involved in an accident which may result in the package falling off the vehicle. external exposure may exist. it is very unlikely that the package will be broken open. are deployed for the transport of radioactive material in India. If the accident is severe such as vehicle rolling over. About the package: Packaging which are permitted to be used for transport of radioactive materials are generally designed to prescribed standards aimed at prevention of release of the contents and of excessive exposure of public of radiation. Protective devices to be carried in the vehicle: The driver of the vehicle and his assistant should each have some protective device if the vehicle carries a package containing dispersible radioactive material. fumes and dust • Wear the coverall. Transport of Radioactive Materials in a dispersible form. All persons who were engaged in the emergency response measures should carefully and thoroughly wash the affected parts of the skin with plenty of water. If the vehicle cannot be release for onward journey for a long time. RSD. then take the following measures: • Assume that the area and the objects on which the spillage has occurred are contaminated. DAE Mumbai–400 001 Tel. summon assistance from the local public and fire brigade. drink or smoke within the cordon • Take measures to prevent a fire accident. 22830441.(off) 022-25990655. Tel. Mumbai. AERB Niyamak Bhavan. Fax:022-22830441. Follow these instructions: • Fight fire as far upwind as possible • Keep out of smoke. Head. segregate the package and cordon a distance of 5 m around the package. ensure onward journey in the same vehicle. Fax:022-25990650 265 . If the contents of the package appears to have spilled.(round the clock) 022-22023978. If the packages appear to be intact. Radiological Safety Division. Mumbai – 400 094. AERB. wrap it in a polythene bag. If there is fire. If the package appears to be damaged. Niyamak Bhavan. 5. Obtain the names and addresses of persons who may have been exposed to radiation and convey the particulars to the Head. using cotton wool. gloves and shoes and cover mouth and nose with handkerchief • Spend minimum time near the package • Keep by standers upwind at least 5 m away Inspect the packages. then arrange for onward journey of the package in some other vehicle. which could not be breathed in. gloves and coveralls • Collect the spillage. Mumbai-400 094. • Do not eat. • Wear the shoes. Fight fire from a distance. • Seek assistance from AERB/BARC as directed in para 5 below • Do not allow the public within the cordon unless so advised by the radiological safety authorities from AERB/BARC. in a polythene bag • Wrap the damaged package in polythene bags • Cover the contaminated objects and contaminated area with polythene sheets. hold a cloth towel or a handkerchief over your mouth and nose. Telephones for advice and assistance for advice and assistance contact: Chairman Crisis Management Group. Anushaktinagar. Anushaktinagar. 27824986 (Res). AERB safety code No. AERB safety code: No. Onward journey of the packages which were damaged in the incident may be arranged only after obtaining clearance from the above authorities. Prior to undertaking the journey. CT and CRS.SG/TR-3:Procedure for forwarding. 6. fire or both. 2. Radiological Physics and Advisory Division BARC. transport. Tel. General: Every driver should ensure that he is completely familiar with the “Instructions in Writing….” the “TREMCARD” the protective devices as specified in para 3 above. The assistant accompanying the driver should also be familiar with these instructions. whether damage/Spillage suspected. • The condition of the packages. BIBLIOGRAPHY 1. • Details of emergency action taken. • The name and addresses of persons who may have been exposed to radiation. • The date and time of occurrence of the incident.. 022-25517812 (Res). the driver should ensure that he carries the following items with him: the ”Instructions in writing….” and the procedures recommended in the TREMCARD. Textbook of Radiological Safety Head. 3. AERB Safety code No. Act exactly in accordance with the instructions given by the above authorities. 022-25519209 (Off). handling and storage of radioactive consignments. • Whether the incident involved impact.SC/TR-3: Emergency response planning and preparedness for Transport accidents involving radioactive material. Fax: 022-25519209 While seeking advice and assistance furnish the furnish the following particulars: • The place where the accident occurred.SC/TR-1:Transport of radioactive materials 266 . Anushaktinagar Mumbai-400 094.. Where as the later two methods are generally adopted in the management of all radioactive wastes. liquid or gaseous form. Protection of environment. Recycling and reuse the waste material. Radioactive waste can be treated some extent by physicochemical methods. However. and iii. which may be in soild. If not handled carefully. Chapter 10 Radioactive Waste Disposal INTRODUCTION Every industry generates some amount of waste and nuclear industry is one among them. suitable for release into the environment. . Delay and decay ii. ionizing radiations emitted by the radioactive waste can cause somatic and genetic effects in the living beings. Minimize the generation of radioactive waste. ii. This period depends upon the half life of the waste. The basic approaches used in the management of radioactive wastes are: i. Protection of human health. effective waste management methods are the need of the hour. Dilute and disperse iii. WASTE MANAGEMENT The basic objective of radioactive waste management is: i. The delay and decay is suitable only for short half life isotopes. Hazards related to radioactive waste give rise to certain amount of fear and unacceptability in the minds of public. adopted to conventional pollutants. Minimize the exposure to operation staff and public. For example I-131 (HL-8 days) in small volumes may be retained till the activity levels comes down to the desired values. Concentrate and contain. they undergo decay and the radiation comes to the background level after a certain period of time. without imposing significant burden on future generations. Hence. Protection of future generation. which vary from seconds to thousands of years. The radioactive waste needs to be managed safely to ensure protection of man and environment. ii. The waste generated in the nuclear industry is called radioactive waste. and iii. To achieve this the methods adopted in the practice includes: i. and this fact may be utilized in the treatment not only of intermediate and high level solid. and disposal of solid and liquid wastes in deep geological formations. may lead later to the exposure of man. tank storage of intermediate – and high-level liquid wastes. The principle is invoked in techniques for air and gas cleaning. . Dilute and Disperse The principle of dilution and dispersion is based on the assumption that the environment has a finite capacity for dilution of radionuclides to an innocuous level. conversion of high-level liquid wastes to insoluble solids by high-temperature calcinations or incorporation in glass. Textbook of Radiological Safety Delay and Decay It is based on the fact that radionuclides lose their radioactivity through decay. and 268 iii. ion exchange and evaporation. Nuclear fuel ii. storage of solid wastes in vaults or caverns. some wastes must be contained for extended period of time. Isotope applications. SOURCES AND NATURE OF WASTE Mainly radioactive waste is generated from: i. the treatment of low-level. solid wastes by incineration. taking advantage of the decay of some radionuclides – particularly those having short half lives – with the passage of time. baling and packaging the treatment of intermediate-level solid and liquid wastes by insolubilization in asphalt. Concentrate and Contain The principle of concentration and containment derives from the concept that the majority of the radioactivity generated in nuclear programs must be kept in isolation from the human environment. The application of this principle requires an understanding of the behaviour of radioactive materials in the environment and of the ways in which the released radionuclides. Since some radionuclides take a long time to decay to innocuous level. It is especially important to take into consideration environmental processes which may cause reconcentration of radionuclides. The principle is especially useful for those installations where a substantial reduction in the activity level of a waste stream can be achieved by delaying discharge of effluents for a few days. particularly those that are considered to be critical. the treatment of liquid wastes by scavenging and precipitation. Research and power generation reactions. The aim is to ease problems in subsequent handling or to lessen risks of releases to the environment. liquid and gaseous wastes but in some cases also in that of low-level wastes. mGy/h Activity. Table 10. Used Brachytherapy sources (Co-60. The third. syringes. Liquid scintillants immiscible with water viii.). which require a comprehensive management system. The solid waste is categoried.81mKr.7 × 108 . CLASSIFICATION OF WASTE The radioactive waste is classified as solid. and I-125). isotope application includes medicine. In nuclear medicine the radioactive waste arises from: iii.and 185mAu etc. In radiothepay the waste arises from. milling. toilet-improper use (vomiting by patients) and decontamination.7 × 103 >3. solid or gaseous with radioactive content varying from insignificant to extremely high levels. Used Tele-cobalt -60 sources. The type of radioactive waste that may arise in medicine are mainly from radiotherapy and nuclear medicine. Radioactive Waste Disposal In nuclear fuel it begins with the mining.g.7 × 10 3. Cs-137. The liquid and gaseous wastes are further categorized on the amount of radioactivity. In India. i.1: Classification of radioactive waste Category Solid Liquid Gaseous Surface dose. liquid and gaseous. vials) xi. >3. Bq /ml I <2 <3. conforming with the internationally acceptable norms and standards. The second type includes isotope production and electricity generation. Laboratory solutions of low activity vi. Radioactive gases. Biologically contaminated solid waste (e. enriched uranium components (shutter.) v.7 × 101 to 3. Wide range of radionuclides are used in medicine for treatment. Bq /ml Activity. leaking sources and contaminated cotton. counting room. nuclear research. as given the Table 10. refining of U and Th from their ores.7 × 10-6 II 2-20 3. Ir-192. industry and agriculture. the Atomic Energy regulatory Board (AERB) has categorized these wastes.7 × 103 to 3.7 × 10-2 IV Alpha bearing 3. and ii.1.7 × 108 - V . source administration and injection needles.7 × 10-2 -2 1 III >20 3.7 × 10-6 to 3. Low activity liquid washings from vials vii. etc. fuel fabrication and fuel reprocessing. diagnosis and research. Decayed sealed sources iv.7 × 10-2 3. preparation. The sources from which the wastes arises are source storage. The waste arises from the above applications are called medical radioactive waste. collimator etc.7 × 10 to 3. depending on the radiation dose on the waste package. Spent radionuclide generators (99mTc. The waste generated may be liquid. 269 . discharged liquid radiopharmacheuticals. blood or body fluids. Textbook of Radiological Safety The liquid waste of categories III and IV need to be properly shielded whereas category V requires shielding as well as cooling during handling. storage. wound and oral discharges. 500 kBq-500 MBq 500 MBq-5 GBq Group 3: 201 Tl. 1mCi-1Ci / litre and 1Ci-100 Ci / litre comes under intermediate and high level waste category. The ICRP-25 classification of nuclear medicine laboratory is given in Table 10. 51Cr. The commonly employed processes and the corresponding decontamination factors are 270 given in Table 10. Where as. 133Xe < 500 MBq *500 MBq-500GBq 500 GBq-50 TBq *supervised areas ** Generator room TYPES OF RADIOACTIVE WASTE Liquid Waste Liquid waste includes contaminated water and effluent. These terms give an idea about magnitude of the radioactive contents and the associated radiation. urine etc. I 125 131 < 500 kBq. where volume involved is small. solvents.2 Table 10. Decontamination factor is defined as a ratio of radioactivity content of untreated and treated waste. The term low level waste (LLW). . A safe disposal is one in which no member of the public should get more than the effective dose limits.2: Classification of nuclear medicine laboratories in terms of activity (ICRP-25) Classification Low Medium High Group 2: I.3. The liquid discharge systems should be 10-4 to 10-5 Ci / ml. intermediate level waste (ILW) and high level waste (HLW) are also employed in normal practice and for day to day working. waste arising from chemical processing and decontamination solutions. 99 Mo < 5 MBq 5 MBq-5 GBq **5 GBq-500 GBq Group 4: 99m Tc. A wide variety of treatment methods are available to meet specific requirement of decontamination. treatment and disposal. Waste trace levels to fractions of mCi comes under low level waste. Low and intermediate active liquid waste from different sources is normally collected and transported to the treatment facility by means of permanent pipelines systems. specially designed tankers are used for collection and transportation. The waste that includes both radioactivity and a hazardous chemical component is referred as mixed waste. The classification signifies the basic requirements for safe handling and disposal of wastes. 32P. In some cases. trisodium phosphate or sodium sulphate. prior to its solidification. volumes involved and climatic conditions. potassium ferrocyanide. Synthetic ion exchangers are also used for the decontamination of the waste. Steam and natural evaporation methods are employed. Mobile transportable ion-exchange system is also in use. Naturally occurring ion exchange materials like vermiculite and bentonite are most commonly used for this purpose. The membrane separates the waste into two components. the concentrate is further treated by evaporation.000 Chemical Treatment In this insoluble flocs of phosphates. Radioactive Waste Disposal Table 10. steam evaporation is preferred whereas for large volumes involving low activity.3: Decontamination factors for various processes Processes Decontamination factor Chemical precipitation 10-100 Ion exchange 10-10. The waste is pretreated for pH adjustment and then filtered for removal of complex agents. These are specially useful for both clean liquids as well as those containing high percentage of dissolved salts. reject and permeate. Reverse Osmosis It is an important process used in the decontamination of low and intermediate level liquid wastes. It employs membranes like polyamide and pressure of the order of 20 kgcm2. Ion Exchange This is the technique used for removal of specific radionuclides from the bulk of wastes. The resulting solids have highly concentrated activity and are subjected to further processing before disposal. copper sulphate and ferric ion are mixed with the effluents in predetermined quantities at an optimum pH value. hydroxides and complex metal ferrocyanides are used to remove radionuclides from the waste. depending upon the activity. The resulting precipitate flocs incorporating radioactivity are allowed to settle and are separated from the supernate liquids depleted in radioactive content. Evaporation It is used for concentrating the liquid waste. Certain selected chemicals such as calcium or barium chloride. sulphates. The volume of waste is normally reduced by a factor of 10 by this process.000 Reverse osmosis 10-50 Evaporation 1000-10. If required. The sludges are further concentrated and dewatered by filtration or centrifuging. For intermediate level and high level waste. 271 . inside surface of the incinerator and in the ash. Burial of solid waste in the ground iii. 272 . and ii. Incineration ii. The solid waste material can be concentrated and disposed by the following methods: i. Incineration Incineration will substantially reduce the volume of wastes. Disposal of Radioactive Solid Waste The waste material is segregated into: i. Sea dumping. Higher activities can be buried or burnt and short lived activity up to 1mCi can be burnt. gloves. hand tools and discarded equipment. metal and glass. The activity associated with the incinerated waste must be restricted to the public exposure limits. Depending upon the physical and chemical characteristics of the compound involved. masks. This method is suitable in reducing the volume of the waste with little escape of activity to the environment. Textbook of Radiological Safety natural evaporation is desirable. Storage of protected material iv. paper wipes. plastics. Non-compressible and non-combustible waste. Sealed sources > 10 mCi should not be disposed and they must be kept for decay. Up to 2 mCi can be disposed as ordinary waste. protective wears. Compressible and combustible. spend radiation sources etc. Solar evaporation process is efficient for tritiated water. overshoes. plastic sheets and bags. worn out metallic parts and equipment and accessories. Solid radioactive waste also consists of general biomedical waste. that includes protective clothing. The incinerators are specially designed to remove the radioactivity from combustion gases by the use of scrubbers and filters and to ensure that the radioactive ash is contained so as to not to cause an airborne hazard. contaminated materials. Occasional release up to 100 mCi in ordinary dust bin is allowed. filters. the activity may be deposited in the gaseous effluents. Very high volume reduction with practically zero release of activity is possible by use of non boiling solar pans. towels. discarded containers. Solid Waste Solid waste is generated at different stages in many different forms which include tissue papers. but the total radioactive content will not be reduced. will reduce the movement of activity in the ground. The amount in the pit should be restricted and the minimum distance between the pits should be 180 cm. In this method one should ensure that the radioactivity is in the form of completely insoluble material. a. A central record should be maintained of all burials. a concrete tomb is constructed underground and the material fed into the tomb via a chute from the surface. The radioactive materials should be packed in steel bins and then must be buried beneath at least 1. and this may therefore be considered under the principle of dilute and disperse to a small extent. Municipal dumps can be used for protected burial.4. the pits can be empted into the municipal dump and reused.montmorrillonite). the identity and quantity of each radionuclide buried in it. The depth chosen for burial must be sufficient to prevent leakage of any harmful level of radioactivity into usable surface waters or ground waters. because it is normally ensured that they carefully sited to prevent contamination of surface or other waters with conventional non-radioactive pollutants. b.5 meters of other rubbish. The choice of burial site is very important and it should be suitably cordoned off. Not more than 12 burial pits per year and after 7-8 half lives. After the tomb is filled up the whole construction is filled with asphalt and sealed.g. Radioactive Waste Disposal Burial of Solid Waste Any site chosen for such burial operations should be examined carefully with regard to its geologic and hydrologic properties and an assessment should be made of the possible contamination of water supplies and of ecological systems that might lead to human exposures. In general. A record should be maintained about the location of each pit. 273 . The maximum disposal limits for ground burial is given in the Table 10. The burial must be carefully controlled to avoid spread of contamination to surface ground waters. In the case of very high radioactive materials. The whole of the burial area and its immediate vicinity should be isolated suitably and fenced to prevent use of the area. Protected material: Highly radioactive materials can also be buried in the soil if a material is treated in such a way that no loaching of the material can occur. Unprotected material: The following method is suitable for low level radioactive waste. this involves packing the waste material in steel drums or concrete blocks. inorder to assure that the area is kept under continuing surveillance. Under such conditions some loaching of the radioactivity into the ground water can take place. The solid type is also important since fixation on a good exchange material (e. The size of the pits is 120 cm × 120 cm and depth of the pit should be such that there should be 120 cm of earth above. Up to 1 mCi can be buried in a municipal site in a form unattractive for salvage. K and in the US both packed and unpackaged wastes are dumped in to water exceeding 1000 fathoms in depth. For low activity solid waste use is made of relatively shallow waters of approximately 100 fathoms. Long lived radioisotopes are stored and disposed to centralized waste management facility. constructed and filled in such a manner as to ensure the following: i. Proper labeling of the container along with records are mandatory. which is the procedure adopted in the country as on date.2 g/cc. The storage area should be in accessible to unauthorized persons. Containers used for sea dumping should be designed. Normally short lived isotopes are stored for decay. That they can not be easily damaged or broken and will reach the bottom with out appreciable loss of contents. To prevent accumulation in working areas. The radiation level at 1 meter should not exceed 1. 274 .5 mR/h in such storages. ii. To avoid dust hazard. Kalpakkam or Mumbai. Usually foot operated dust pins with plastic bag is used in hospitals to store solid waste. There the waste is disposed off in engineered structures such as reinforced concrete trenches and the tile holes depending upon the waste and the radioactivity. it is stored and then returned to the supplier. Sea Dumping This method of disposal for solid active waste can be carried out after carefully choosing an area on the basis of oceanographic studies. They have density of 1. To provide shielding. and iii. ii.4: Disposal limits for ground level Radionuclide Maximum activity in a pit (MBq) 3 H 9250 14 C 1850 24 Na 370 32 P 370 35 S 1850 45 Ca 370 59 Fe 370 99 Mo 370 125 I 37 131 I 37 Storage The purpose of protective storage is: i. In the case of Brachytherapy solid wastes. Textbook of Radiological Safety Table 10. iii. BARC. They are free from voids. This method is practiced in the U. The ventilation exhaust system is provided with suitable devices to contain airborne radionuclides. Therefore the airborne activity in the working area should be kept within limits (Table 10.5). The emission of activity to the atmosphere may give rise to three possible types of hazard: (i) a direct irradiation hazard from the radioactive clout itself or from material which is deposited on the ground. In addition. (ii) inhalation hazard to people breathing the cloud. it is highly desirable that careful records are maintained of the total activity content and weight of all consignments. This may be achieved by providing separate ducking systems for radioactive and non radioactive effluents and filtration system for the radioactive fraction alone. Although no general legislative control exists for the dumping of material outside territorial waters. and (iii) an ingestion hazard from material that finds its way into food chains. They are of a size and shape to be handled quickly and conveniently. The exhaust gases are treated for removal of and retention of particulate activity by using high efficiency particulate air (HEPA) filters along with other cleaning techniques. The type of hazard depends on the circumstances of a particular emission. negative pressure compared to atmosphere is maintained in the working areas to restrict the release of activity to the environment. fission products. For most isotopes the hazard is usually caused either by first or third types.5: Air concentration that would result annual dose limits to occupational workers Radionuclide Air concentration borne (μCi / ml) 18 F 3 × 10-5 99m Tc 6 × 10-5 131 I 2 × 10-8 14 C 1 × 10-6 133 Xe 1 × 10-4 275 . Radioactive Waste Disposal iv. Gaseous Waste Gaseous waste management is very important to take care of airborne radioactive particles and gases. The removal of particulate and gaseous contaminants from gaseous effluents is a complex and expensive one. They are provided with sufficient shielding for safe storage. It is advisable to design the plant and buildings so that the volume to be treated is as small as possible. The main contaminants of importance in nuclear facility are radio-iodine. Table 10. Once the effluent is released in the air the operator has no control and hence can not escape the consequences arising out of air pollution. tritium. v. noble gases etc. Release of the liquid wastes at small rates over long periods of time. For the disposal of liquid wastes into rivers the following factors should be considered: flow rate. In addition. Detailed biological experiments must also be done to determine the pattern of up take of radioactivity by marine fauna and flora. It will depend upon the proximity of the facilities producing or treating the wastes to the types of environment mentioned aforesaid. DISPOSAL OF RADIOACTIVE EFFLUENT INTO THE GROUND The liquid waste injected into the ground will tend to percolate downwards until it reaches the ground –water table. as drinking water tolerances are not involved. streams or the sea. Hence. c. b. by the time the waste reaches the environment. Disposal of diluted waste can be done into the sea. Release of wastes into large bodies of water. turbidity. dilution may be partly off set by concentration of some radioactive species in marine life which may enter into feed cycles ending in consumption by human beings. the activity is diluted by the natural water flowing in the ground. Sea is a unique medium for disposal of low activity waste because dilution. industrial and agricultural uses and appropriate correction factors should be applied to arrive at the permissible discharges. The factors determining the applicability of . Addition of uncontaminated liquid to reduce the concentrations prior to discharge. when it begins to travel forward in the direction of underground water flow. nature of river bed. Textbook of Radiological Safety DISPOSAL OF LOW ACTIVITY WASTES INTO THE ENVIRONMENT The principle involved is dilute and disperse. factors are large and maximum permissible levels for discharge are higher than those for fresh water bodies. Dilution of low- level liquid wastes can be achieved by a. by discharging to springs. in doing so. especially those involved in food cycles. any projected sea or river disposal scheme must be preceded by extensive trails to determine the dilution of foreign solution discharged at various points in the sea or river. By these the degree of horizontal and vertical mixing is obtained on discharge to the sea or river as well as the effects of winds and tides upon the dispersal of the material. if the permeability and porosity of the formation are such that underground water is appreciable in volume but not too rapid in rate. and in very favorable circumstances very high retention 276 times may be encouraged. currents etc. Consideration must be given to the types of water utilization such as drinking. river or into the ground. However. The retention time may be extended by chemical reactions between the waste and the soil. the combination of dilution and the decay afforded by an appreciable retention time may be such that the waste levels are below the dose equivalent limits. 7). iii. and in soils rich in organic matter to the humus content as well. Although the ground water flow may then be slight. when the flow in a sewage system is 4. iii. where the patient administered with radioactive isotopes is allowed to use the toilet without restriction. where the radioactive material is collected in a 5 litre bottle. Any waste disposal method must take into account the following: i. The precipitation characteristics will depend upon the natural pH of the soil. . and (iii) constant drip discharge: In order to maintain a uniform discharge in case where the activity to the disposed of is more than 10 mCi of P-32 and I-131 a day for 4.5 million litres of sewage flow. Appreciable permeability to allow rates of flow sufficient to be useful. DISPOSAL OF P-32 AND I-131 INTO MUNICIPAL SEWERS BY MEDICAL USERS The various waste disposal methods are (i) toilet disposal. especially with regard to sanitation workers and sewage plant personnel (Tables 10. Ion exchange properties of soil depend upon the type and amount of clay minerals present.5 million litres during dry weather. (ii) Batch bottle disposal. ii. Radioactive Waste Disposal ground disposal methods are two. To formulate practicable rules and activity discharge based on the average water consumption and average isotope concentration level arising there from. diluted to the top and poured into the sink. A deep water table with good flow gradients. In addition to the hydrological phase retention in the ground there may be further retention of certain species due to chemical reactions with constituents of the soil or rock. As a rule of thumb. The desirable factors for hydrological factors for ground disposal can be summarized as follows: i. In any case ground disposal requires detailed study of hydrological and chemical characteristics of the soil where the disposal is contemplated. it is necessary to use a constant drip discharge bottle. v. Permissible concentrations applicable from the standpoint of community safety. To ensure that the degree of dilution envisaged will be at the discharge point from the institution into the sewage system into which the 277 radioactive wastes are discharged. Relatively low rainfall. up to 100 mCi of P-32 or I-131 may be discharged through a constant drip discharge bottle during a 6 hour day light period. namely (i) hydrological. Wide spacing of water bodies such as lakes and streams so that long distances of underground flow are involved. the porosity of unsaturated formation in an area of low rainfall may afford high retention volumes. These reactions are precipitation and ion exchange. and (ii) chemical.6 and 10. The limit is subject to revision depending upon variation in flow rate and actual radioactive measurements in the sledges. ii. iv. A fairly high porous thick formation to restrict rates of flow. 7 222 32 P 3. Waste materials from the drawing up of patient injections can be divided into two groups.7 28.5 740 24 Na 3.5 3700 14 C 18.7 22. Long half-life or high activity waste may need long term storage in a suitable storage area.7 22. vi. Textbook of Radiological Safety iv.2 278 . water and sewer concentrations that would result annual dose limits for public Radionuclide Environmental concentrations (µCi/ml) Sewer Air Water concentration (μCi / ml) 18 F 3 × 10-9 3 × 10-5 3 × 10-4 99m Tc 2 × 10-7 1 × 10-3 1 × 10-2 131 I 2 × 10-10 1 × 10-6 1 × 10-5 14 C 3 × 10-9 3 × 10-5 3 × 10-4 133 Xe 5 × 10-7 — — DISPOSAL OF RADIOACTIVE WASTE FROM NUCLEAR MEDICINE PROCEDURES Radioactive waste from nuclear medicine procedures can be dealt with either by simply storing the waste safely until radioactive decay has reduced the activity to a safe level or possibly by disposal of low activity waste into the sewage system.7: Disposal limits for sanitary sewage systems Radionuclide Maximum limit on total Average monthly concentration of discharge per day (MBq) radioactivity in the discharge (MBq / m3) 3 H 92.7 185 125 I 3.5 35 S 18.1 99 Mo+99mTc 3.5 74 45 Ca 3. if permitted by the local regulatory authority. v.2 131 I 3. to ensure that the external radiation hazard to sanitation and sewage plant personnel will not be more than that caused by accidental immersion in a concentration of 0.6: Airborne. Table 10. To bear in mind that it would be unreasonable to insists upon the dilution of radioactive waste in the sewage to the level established as maximum permissible limits for drinking water. those with long and those with short half- lives.7 10.1 mCi / litre of sewage. The hazard to the general population in the event of the sludge containing radioactive material being used as fertilizer. Table 10. 10. a biological waste bag. for example. Each type of waste in nuclear medicine requires special consideration since biological contamination (e. Possible build up of activity in irrigated land and crops to be considered. Table 10. 5. attention should be paid to the following points: 1.8. The effective dose limits should not be exceeded.4 μCi) 1 × 107 (270 μCi) Group 3: 201 Tl.1 mCi / litter. The radiation hazard to sanitation workers and sewage personnel < that from accidental immersion of 0. The container should be labeled with the radionuclide and date. I-131 and other longer half-life materials should be placed in a separate labeled and dated plastic bag and stored safely. 99Mo Group 4: Tc. in a plastic bag inside a shielded container. 58Co. 4. Records should be kept listing initial activities and recommended disposal dates for medium and long half life nuclides. 3. 7. 8. should be separated and placed in a shielded plastic container for safety. 32P. 131I 5 × 104 (1. 9.99mTc waste should be kept for an appropriate decay period before disposal (24h). 51Cr. Sharp items. Long lived isotopes other than 3H and 14 C should not be released to sink. blood) may be a more series hazard. A controlled disposal is defined as disposal with permission from the regulatory authority. Total activity released should not exceeded 1 Ci / year. 67Ga. Waste should be placed in a locally appropriate waste disposal container.8: Discharged activity limits for non controlled and controlled conditions Classification Non controlled (Bq) Controlled (Bq) Group 1 — — Group 2: 125I. 5 × 105 (14 μCi) 5 × 106 (140 μCi) 111 In. 2. no record normally required for decayed 99mTc contaminated items. Any labels and radiation symbols should be removed. When disposing of waste.4 μCi) 279 . If the effluents is used for agricultural purposes the levels should be reduced by 10. Accepted levels for disposal of radioactive waste under controlled and non controlled conditions are given in Table 10.g. Normally once the surface dose rate in any individual bag of waste is below 5 mGy/h it can be disposed of. 6. 57Co. Disposable gloves should be worn and caution exercised when handling sharp items. Radioactive Waste Disposal Technetium-99m waste normally requires storage for only 48 hours. 133Xe 99m 5 × 106 (140 μCi) 5 × 107 (1. Formulate practicable rules and discharge levels based on average water consumption and isotope concentration. Gallium-67. such as needles. Patient Waste Special toilet should be available to nuclear medicine patients. Spent generators should be removed to a separate store room or bunker for the required decay period. Overalls (Boiler suit) These are one-piece cotton drill garments so designed as to cover the body completely except for the head and neck. It is recommended that the pattern . and feet and angles. so that the exposure should not exceed the effective dose limits. Storage room should be provided with shielding. an apron of suitable impervious material such as PVC. ROUTINE PROTECTIVE CLOTHING Laboratory Coat Conventional white cotton drill or nylon coat of proper size which should extend below the knees are suitable for clean areas. rubber gloves of a heavier type or leather gloves may be used to reduce the beta radiation dose to the hands. Rubber Gloves For general laboratory work. Patient’s excreta are exempted from disposal restrictions. The fastenings for these garments are usually at the front. Textbook of Radiological Safety 99m Tc Generators A Mo-99 generator with activity of 345 mCi decays to 140 μCi after 31 days. Polyethylene or neoprene will be found useful in preventing the clothing below from becoming contaminated by corrosive liquids or dust. The toilet should have direct access to the sewage system and should not run under the nuclear medicine department. Aprons In areas in which the processes involves work at benches with liquids. It can be disposed under controlled conditions with proper authorization. Where it is necessary to handle beta active material directly with the hands. since high activities will affect the performance of counters and imaging devices by increasing background activity levels. surgical gloves are adequate for most operations. Urine and feces should be discharged using a toilet connected directly to a main sewer. Foot Wear These should be preferably rubber-soled to prevent the uptake of 280 contamination and to facilitate cleaning. They are extremely useful as they protect all the clothing worn below. wrists and hands. For work in areas of very low activity a half-face respirator may be used. A cheaper form of overshoe made of rubber. such as in areas being decontaminated. Rubber Boots These are particularly useful for wear in areas in which the processes involve contaminated solutions or wet conditions. Skin and Surface Contamination In decontaminating the skin. The conventional rubber overshoes are suitable but the soles should not be too deeply indented. In such cases. Radioactive Waste Disposal of the rubber sole should not be too deeply indented. Care must be taken to ensure that these respirators fit properly and do not allow air to be taken in from the sides of the face-piece. Radioactive contamination may exist in loose form or may be more or less fixed as a result of physical and chemical factors. plastic or canvas is also available. suggested types are the resin wool and charcoal or the highly efficient paper filters which are commercially available. while it would be ideal to remove the entire contamination. DECONTAMINATION PROCEDURES Decontamination is the process of removal of radioactive contamination from the skin or from surfaces such as the wall or floor of working areas. The upper part of the shoes should be well waxed to resist the absorption of contaminated solutions. The filter used must be reliable. because the drastic measures which may be necessary in certain causes could result in such damage to the skin that the radioactive material could gain entry into the body and so give rise to an internal hazard. this may not always be possible. Whenever possible contamination should be cleaned up as soon as it occurs. it should be considered satisfactory to reduce the levels of contamination to 281 . Overshoes These are worn over the normal walking shoe and are suitable for use by visitors to active areas or for general use in laboratories. a full face respirator with an efficient filter provides adequate protection. Breathing Apparatus For work in areas of low or medium level of airborne activity. The soles of these boots should not be too deeply indented. This further prevents the spread which makes the eventual decontamination more necessary. The half length rubber boot is usually adequate for this purpose. The soap chosen should be mild to that it will not produce skin damage after frequent use. the next action are aimed at removing the contamination before decontamination can be started a careful survey must be carried out over the entire body with a suitable contamination monitor to determine the location of the contamination. with a view of letting the activity die down naturally to within permissible level. Mild decontamination method should be tried before resorting to treatment which can damage the surfaces involved. contamination involving short lived activities should be isolated and segregated to allow natural decay to take its course. be situations in which experimental requirements render it essential that the decontamination be absolute. Decontamination of Personnel Once a radioisotope has become lodged in the body. Precautions must always be taken to prevent the further spread of contamination during decontamination operations. Following any necessary medical treatment. and table tops. contamination incidents are bound to occur and so a knowledge of the current treatment is vital. In the case of partial contamination it is only necessary to contaminate the affected areas. The above considerations imply the setting up of maximum permissible levels of contamination for the skin and for surfaces in controlled and uncontrolled areas. Particular attention should be given to the nails. it might turn out to be more economical to store the contaminated object temporarily. The first action when dealing with a contaminated person is to ascertain whether or not he is injured. c. or to dispose of it as waste. There could.The fundamental principles which are applicable to all decontamination procedure are. and for contaminated equipment. This means that every effort must be made to prevent contamination entering the body. in dealing with contamination of certain articles and types of equipment. d. Wet decontamination method should always be used in preference to dry. Textbook of Radiological Safety within permissible limits. . Similar considerations would apply to the decontamination of surface such as walls. Where possible. For hands. soft-bristle nail brush should be provided for use in conjunction with soap and water over the entire surface of the hands and the wrists. Frequent rinsing is 282 essential during the entire operation. very little can be done to increase the rate of elimination. If he has a serious injury then he must be given first-aid treatment as quickly as possible. On the other hand. to the ridges between the fingers and to the edges of the hand. Soap and water is the first requirement for removing contamination from the hands and other exposed areas of the skin. however. a. floors. Even so. To this end it is vital that all personnel should obey the house rules and always wear the correct protective clothing. b. In case of contaminated small open wounds. the individual concerned should be referred to the medical department where more effective decontamination can be carried out under medical supervision. This has an important application in the even of a reactor accident. antacids or ion exchange resins. All corrective measures should be carried out under medical supervision. When contamination has been swallowed. The latter is particularly important to ensure that contamination removed from the hair does not remain in the ears or on the face. or other materials suitable for drying. All personnel should be instructed to keep the eyes and the mouth closed during treatment and to rinse the fact frequently with copious amounts of water. the wound should be immediately washed. Contamination of hair should be washed several times with an efficient shampoo and copious amounts of water should be used for rinsing.. Unfortunately. Certain chemical called chelating agents may be administered to promote excertion. Decontamination of Working Areas A preliminary contamination survey will indicate those areas which require decontamination and such areas should be clearly marked. The decontamination measures should be restricted to those areas and every endeavor should be made to prevent the spread of contamination. e. punctures etc. the uptake of radioiodine to the thyroid can be greatly reduced by previous ingestion of a 200 mg tablet of potassium iodate. For example. The decontamination measures taken will depend upon the nature of the contamination. In the event of contamination which persists even after the above- mentioned procedure have been followed a number of times. and 283 . rubbing should be avoided. are absorbed through a wound or inhaled in a soluble form. may be administered promptly after the intake.e. All cases of face contamination should be referred to the medical officer. The absorption of certain radioisotopes can be blocked by the prior ingestion of substantial amounts of a stable isotope of the same element. While using towels. Whenever internal contamination occurs.g. bleeding should be encouraged if necessary. copious amounts of water and soap should be used. parallel in some ways to the absorption of chemical toxins. i. whether it is in loose form or is reactively fixed. it essentially becomes a medical problem. Isolated areas of high contamination should be carefully scrubbed. substances designed to prevent or reduce absorption from the gastrointestinal tract. the hands alone being used to create the lather. It is essential that skin decontamination should not be taken to the point of damaging the skin. and the medical officer should be consulted. such as Pu. these substances tend to be chemically toxic themselves. If radionuclides of high toxicity. Radioactive Waste Disposal For the face. cuts. a suitable strippable lacquer may be carefully applied to the contaminated surfaces. For all other surfaces. The decontaminating solutions to remain in contact with the contaminated surfaces as long as possible so that chemical reaction at the surface may assist the decontamination. the affected areas should be washed as described above. More stringent treatment would involve the use of steel wool or a similar scouring agent. care should be taken in using the spraying device to avoid disturbing the loose contamination and thus giving rise to an airborne hazard. No attempt should be made to brush or dust it off. Textbook of Radiological Safety details of decontamination procedures are given in this order in the following sections. personnel should be in fully protective clothing. Contamination remaining after several attempts at removal with the above treatment will normally be confined to small areas (unless a major spill has occurred) and further proprietary abrasive cleaners are useful for general application in this spotting treatment. In the latter case. After shipping. precautions should be . Decontamination solutions which contain complexing agents are particularly useful in such cases. Removal of Loose Contamination Special decontamination apparatus. wet methods such as webbing are essential. unless it is so fixed and in such small 284 amount that it can be left in place. such as vacuum cleaners fitted with special filters. If contamination persists. Only light rubbing should be used at this stage and the swabs should be discarded frequently as radioactive waste. During this operation. Removal of relatively Fixed Contamination Only wet methods should be used. though in the case of slight contamination on the floor a wet medium such as dampened sawdust sprinkled over the contaminated area before brushing is acceptable. abrasive creams containing a complexing agent. The removal of contamination should be done with the minimum of rubbing and the swabs should be frequently discarded as radioactive waste. may be used to remove loose contamination. This lacquer is allowed to dry and in so doing will take up the contamination. As a precaution. Afterwards the strippable lacquer can be removed together with the contamination. Where there is copious loose contamination. may be rubbed into the affected areas and left in contact for a period before being washed off. Metal polish can be used to advantage on metal surfaces. Contamination remaining after this treatment should be removed by further washing with suitable decontaminating solutions. it will be necessary to remove the surface on which the contamination is fixed. The first wash should be with suitable detergent solution which will remove loose contamination and all grease- held material. Contamination left in situ over periods of time becomes fixed and becomes increasingly difficult to remove. Decontamination methods for equipment are of two kinds: a. paint or other appropriate material. since damaged surfaces may be unsuitable for reuse because of their tendency to collect contamination easily. In the latter. d. the only difference being in the reagents used for various materials. when contamination still remains after the above treatment. All decontamination should be carried out using wet methods. Further methods will depend upon the extent and nature of residual contamination. Decontamination of equipment should be carried out as soon as possible after its removal from the active area. and is left there for suitable periods of time. In all cases the first method should be used initially and only if several attempts fail should the second method be tried. If the contamination is present in spots. such items of equipment may be conveniently classified into groups according to the material of which they are made. Decontamination of Equipment It is impossible to describe here the measures to be used in the decontamination of the individual pieces of equipment encountered in radiation work. This will remove all loose and grease-held contamination. e. This may be followed by swabbing and light scrubbing with the same solution. Removal of the surface of the equipment together with the adhering contamination. The routine to be followed is the same for all equipment. a treatment known as spotting may be carried out using abrasive or strong acids on the small 285 . c. The routine procedures are: a. Radioactive Waste Disposal taken to seal in the contamination with concrete. Removal of contamination without damage to the surface below. b. Equipment is washed in clean water on removal from the decontamination solution and is then dried before being monitored. where contamination remains after the above treatment. preferably at raised temperatures. and the decontamination. Further scrubbing and also steeping technique may be used. Decontaminated equipment should be washed in clean water and dried before monitoring. b. suitable precautions can be taken against dispersing the contamination and creating a hazard. Such sealed in contamination must be recorded so that in any further modifications to the building. Wash in detergent solution at raised temperature. However. the equipment is placed in solutions of suitable decontaminating reagents. The inclusion of complexing agents in the decontaminating solution is recommended to prevent redeposition of the contamination. f. Special apparatus in the form of fume hoods or gloves boxes will be necessary for the acid treatment. Special arrangements are made for laundering clothing worn in contaminated areas and the effluent from laundry facilities is treated as liquid radioactive waste. When there are substantial levels of airborne contamination it is usually necessary to have a fully-enclosed dry suit and a filter mask or a mark fitted with an air supply. fire. because of noxious fumes. Precautions should be taken to prevent the acids from damaging the surface of the equipment more than is absolutely necessary to remove the contamination. Suitable stowage on the non-active side of the barrier for the workers’ personal clothing. For low levels of surface contamination an ordinary laboratory coat with overshoes and gloves may be sufficient. d. Notice boards at the barrier. a hand and clothing monitor). the clothing to be worn and any other precautions to be taken. when the contamination is in liquid form. but if this fails. Consideration must also be given to suitable emergency exists. the hazards in the area. Equipment should be well washed and dried before monitoring. Whatever the standard of protective clothing. stating ‘no unauthorized entry’. results in the contamination being fixed and renders . Decontamination of Protective Clothing Routine protective clothing should be cleaned regularly to avoid the build- up and fixation of contamination. as experience indicates that such storage. Wash hand basin (and possibly a shower) and monitoring instruments (for example. For similar reasons. Where acid are used. b. it is often necessary to wear a fully enclosed PVC suit with a filter mask or fresh air supply. c. it may be possible to apply abrasive over the whole surface. f. Containers for used clothing and radioactive waste. care should be taken to ensure that the surface of the equipment is not unduly etched. should be posted in the area. Emergency instructions: Detailing actions in the event of possible incidents such as critically. steepage in acid solution will be necessary. Textbook of Radiological Safety areas involved. serious personal contamination. e. the change and barrier arrangements must be efficient and should have the following facilities: a. Protective Clothing The protective clothing requirements in a contaminated area depend on the nature and amount of the contamination. Conveniently-placed protective clothing ready for use. the clothing should 286 not be left in storage for long periods before cleaning. Again. If the contamination is general. since it can give rise to airborne contamination. sodium acid phosphate and citric acid has given good results with this type of clothing. Bulk collection of contaminated gloves is most unsatisfactory. since there is no efficient way in which they may be washed in large numbers without transferring contamination to the inside. Good-quality soap or detergents and scrubbing brushes should be provided at appropriate places where personnel may wash their gloves. Contaminated clothing should be handled as little as possible. sodium metasilicate. Rubber Gloves It is essential that the personnel wearing these gloves. The reagents or soaps used will also depend upon experience. but a washing solution consisting of unbuild detergents. The process used in cleaning this type of clothing is not dissimilar to the processes adopted in conventional laundries. but as a guide it is usual to give clothing two full washes (of 10 min each) with a rinse (of 5 min) in clear water after each wash. which have proved economical and more satisfactory than paper towels. before washing. The detergent used should be mild one and unlikely to cause skin complaints if it comes into contact 287 with the faces of individuals. White Coats and Coveralls In small establishments it will not usually be necessary to segregate this clothing. Another measure taken in such clothing to avoid build-up and fixation of contamination is to provide no pockets or belts and to minimize folds. and particularly the heavy rubber gloves. It is useful to remember that the more stringent washing solutions used necessitate the use of suitably resistant metals in the construction of washing machine. The small towels should be used once only and then placed in a suitable collecting bin. . However. should wash them on completion of their work. in larger establishments where a variety of radioactive material is used. The gloves should be well scrubbed and rinsed and then dried with paper towels or preferably with small pieces (say 2 x 1 ft) or toweling. Radioactive Waste Disposal decontamination increasingly difficult. it is often necessary to segregate the clothing to prevent cross contamination during the cleaning process. The actual routine of washing will depend on experience. according to the different contaminants and different levels of contamination. Respirators and Dust Masks The only satisfactory way in which these items may be cleaned is by individual swabbing with suitable detergents. The clothing should be dried thoroughly before being monitored. et al. Suitable detergents should be used for washing these suits and it is also advantageous to use solutions containing weak citric acid and completing agents such as ethylene-diamine-tetra-acetic acid (EDTA). Mumbai 2001. BARC. New Delhi 2004. Impressive Protective Clothing On completion of an operation involving the use of this kind of clothing and where extra contamination is expected.) Saunders. Simon RC. The soles should be scrubbed with detergent and complexing solutions. . Resistant contamination will necessitate the removal of the rubber surface by acetone or mechanical buffing. Afterwards the suits should be rinsed in clean water and quickly dried. et al. if kept properly waxed. Physics in Nuclear medicine: (3rd edn. The fact- pieces should be well swabbed with clean water. Textbook of Radiological Safety Small cloth or cotton swabs should be used all over and inside the face- pieces. 2003. Where mechanical buffing is used. There is obviously a need to choose the correct position for this so as to prevent dispersal of contamination. Chandrani L. and it should be followed by washing with detergent and soap solution. it will be necessary to provide for local air extraction on the machine. and for resistant contamination it may be necessary to remove the surface of the rubber by the application of acetone or by mechanical buffing. Footwear Rubber-soled shoes may require decontamination from time to time. London 2006. Operations in these suits usually involve at least two individuals and it is a convenient practice for them to wash each other. 4. Any residual contaminating can be treated separately with mild abrasive pastes or similar material. Rubber boots should be cleaned after each operation. Foundation books Pvt. and then dried. et al.). Scrubbing in detergent and complexing solutions should be followed by the use of abrasive pastes necessary. et al. 3. Kanwar Raj. Radionuclides in Bio-Medical sciences-An introduction. The Physics of Diagnostic imaging: (2nd edn. When dry. 2. Care should be taken to clean the outside first and then the inside using clean swabs. Hodder A. David JD. it is essential that the operator. Precautions should be taken to prevent contaminated liquids from entering the boots. can be easily decontaminated. Management of Radioactive waste: Indian association for 288 radiation protection. C/o RP&AD. still wearing the suit should pass though some form of washing. These swabs should be changed frequently.Ltd. assisted by swabs and soft bristled brushes. The upper part of the shoes. following the detergent treatment. BIBLIOGRAPHY 1. the suit is removed and monitored. This may consist of an installed shower or simply of a rinse with buckets of water. Transport of radioactive substances). In such places where there is potential for accidents. On-site accidents: High levels of exposure to radiation occur as a result of a person inadvertently entering a high radiation field. 3. (ii) provision of visual or aural indication to identify high radiation level areas. As a result of which persons in the adjoining room who may not even routine radiation workers could be exposed to relatively high levels of radiation. Accidental external exposure to excessive amounts of radiation (e. TYPE OF RADIATION ACCIDENTS 1. and (iv) the absorption of detailed administrative procedures such as provision . health and property. Accidental spill or explosion in a working place resulting in surface and air contamination of the surroundings and contamination of personnel. appropriate control measures should be taken well in advance to ensure that the chances of any person being accidentally exposed to high levels of radiation are minimized. Radiation accidents would normally conform to one of the following: 1. A radiation accident could occur at any stage of an operation involving radiation sources. (iii) provision of adequate radiation alarms which can be either located at strategic points or carried by individuals whenever they are near high radiation level areas. A person remains inadvertently close to a strong source or accidentally exposed to beam of radiation). Dispersal of radioactive material to the environment as a result of an explosion. through open wounds or absorption through skin. In such cases the intake of radioactive substances into the body could be by inhalation.g. Chapter 11 Radiation Emergency A radiation accident is an unusual occurrence resulting from the loss of control over a radiation source which could directly or indirectly involve hazards to life. mechanical shock or other incident occurring in a public place (e. Such measures includes (i) the provision of interlocks which could ensure that no person can enter the radiation area when the exposure is in progress. 2. when the machine is ON. For examples. For example. a beam of X-ray could be inadvertently turned towards a wall to which it should not normally be directed. a person walking towards the X-ray beam.g. fire. resulting in high contamination of both surface and air in the vicinity. Radioactive contamination may be external or internal. unless it is accompanied by traumatic injury. Off-site accidents: This type of accident may occur in areas to which public have access and may result from one of the following contingencies: i. External contamination can occur as a result of spillage of radioactive material on skin or hands coming in contact with loose radioactive material. In the case of external irradiation. The inability to get a remotely controlled source back into its shielded container because of mechanical or pneumatic failure. iv. Internal contamination occurs most often as a result of inhalation of radioactive materials in finely divided form. Accident to consignments of radionuclides when such consignments are in a carrier such as a truck. If the possibility is high.g. 3. first aid is not required. Accidental breakage of a sealed source or the container of an open source. ii.partial body exposure or localized skin exposure. Textbook of Radiological Safety of suitable cordoned–off areas and prohibition of entry into such areas during radiation operations. Unplanned release of airborne activity to the environment of a radiation facility owing to unusual conditions such as fire. As mentioned above. In order to minimize the long term sequela. Accidents which could involve fire or explosion and which could result in the breakdown of the integrity of shielding or dispersal of radionuclides in the environment of the laboratory (e. if the integrity of the skin is lost due to wounds. abrasions or chemicals. A second category of accidental radiation exposure. Internal contamination can also occur as a result of eating with contaminated hands or consuming contaminated water. iii. which is quite uncommon. breakdown of the ventilation system or breakdown of the filter system. ii. it may also occur when contamination present on the skin penetrates the outer layer and enters systemic circulation. Classification of radiation accidents: Accidents involving radiation sources and radioactive minerals can be generally classified as (i) external radiation. explosion. it is . External radiation can result in whole body exposure. or when such consignments are held in storage during transit. Break down of crucial ventilation systems in areas where open sources are being handled. train or aircraft. and (ii) radioactive contamination. criticality accident in nuclear reactor). In radioactive contamination there is no 290 immediate risk to life. which could arise in a radiation work area.It can cause irradiation of the skin and underlying tissues as well as provide a potential for the material to enter the body subsequently. could result from one of the following contingencies: i. 2. which are not common. Some times they are telescopically coupled to the meters. Arrange for immediate availability of experts. In the case of personnel contamination. 1. segregate and treat all persons who are exposed to radiation. The following guidelines may be adopted during emergency. carry out decontamination. If the radiation fields are higher. 4. Contain contamination within the accident site. Such instruments should be periodically calibrated and kept in good working conditions. both external and internal. that room must be immediately isolated from its surroundings by shutting off mechanical ventilation and by closing windows and doors. Regulate entry to the area of accident. 291 . for analysis. who are trained to deal with emergencies. Biological monitoring and body burden measurements must also be conducted immediately. 3. if administered to the person within a short period at the accident place is sufficient. Arrange immediate evaluation of their TLD badges and collect samples from body fluids such as blood. Notify promptly to the appropriate authorities through media such as fax. A room with heavy air contamination will be decontaminated from within by drawing the air of the room through an appropriate filter. clean up the contamination immediately. so that further exposures and contamination may be prevented. Routine protective measures such as wearing gloves and segregating the mop as radioactive waste should be adopted. so that the detector would be in close proximity with high radiation field and the person reading the meter is away from the radiation field. The instruments required to carry out this work should also be made available. In case of radioactive liquid spillage. Emergency Procedures The first step in dealing with radiation accident is to identify. and seek suitable advice. urine etc. mobile and telephone. Immediate steps should be taken to assess the extent of exposure by sending the personnel monitoring TLD badges used by the exposed persons for dose evaluation. These instruments must cable of measuring much higher dose and dose rate. 5. Air and surface contamination samples should be analyzed urgently to take further action. Evacuate the immediate area. Identify and isolate all persons. First aid. 2. who might have exposed or contaminated. Entry into the room except the experts should be forbidden. 6. If there is relatively large release of radioactive powder or aerosol in the room. Radiation Emergency necessary to block or minimize systemic uptake and hasten the biological elimination of the contaminant. by ensuring that the radiation field and the extent of contamination is kept minimum. special radiation measuring devices will be required. 2. The staff are instructed in basic emergency procedures including the persons to be contacted in case of an accident. the area should be cordoned off and appropriate authorities will be contacted for further action. 9. Determine and periodically review the availability and location of trained personnel. Textbook of Radiological Safety 7. 8. Ensure that he is prepared. the user should establish an internal organization. 6. Define the authority to be notified in the event of a radiation accident. Provide assistance to public authorities as required. within the limits imposed by his resources. These public authorities will: 1. Responsibility in the Control of Radiation Accidents The responsibility for controlling the use of radiation sources with in country should rest on the public authorities and the users of the source. 7. Priority should be given to human safety and the personnel dose should be restricted with in limits (ICRP has recommended 10 rem dose limit for planned special exposures). that will: 1. Prescribe protection standards and guidelines. 3. In accordance with the requirements of his work and regulations applied by the public authorities. Arrange for assistance from public authorities and other off-site organizations if necessary.up operations for dealing with complicated situations associated with high radiation fields and contamination areas should always be part of a radiation emergency procedure. Arrange for control of the uses of radiation sources through licensing and regulations. 292 .The government should designate and define functions of those public authorities which are responsible for the control of radiation sources and dealing with radiation accidents. Provide immediate notification of the designated public authorities of accidents whose consequences may extend off-site. and all other necessary equipment and services. Determine the need for trained personnel in the sate and arrange for training. resulting in enormous complications in investigating such incidents and in the adoption of subsequent remedial measures. This simple instruction is often not followed. 4. If the accident is in the public area. 5. Establish lines of authority among national bodies. to deal with any accident that may occur within his premises. The same may be displayed at suitable locations in the radiation installation. 3. Establish necessary liaison with national authorities in neighboring countries. 2. 4. Maintain complete records of the accident and follow up procedures. if necessary. Mock. The responsibility for immediate action following an accident originating with in the establishment will rest on the operator or user. If the individual concerned undresses it is more than likely that he will become contaminated from the active material present on that suit. These comprise a well fitted face piece in which suitable goggles are inserted. Breathing Apparatus When compressed air supply is not available for use in the pressurized suits described above. Fully Impervious Clothing This consists of garment so designed that they cover the individual completely. which implies removal of all personnel clothing and the wearing of simple clothing supplied by the laboratory. Complete protection of the hands and wrists is afforded by wearing rubber gloves. socks and shoes. A typical change would be drill trousers underwear. This face piece is 293 . Keep adequate records. Radiation Emergency 5. Finally complete exclusion from contamination is obtained by wearing rubber gauntlet gloves pulled well over the cuffs of the protective suit and rubber boots with the bottom of the impervious suit trousers brought over them. including fully impervious clothing. Provide notification of designated public authorities of all radiation accidents. breathing sets may be used. 6. Rubber boots are usually worn with the suit. Before wearing emergency protective clothing. Assistance is always necessary to dress an individual in any impervious clothing. which are securely taped to the suit to prevent the ingress of any contamination. hoods of similar material are used. Emergency Protective Clothing Provision of the protective clothing is usually indicated in areas where the operations concerned will expose the personnel involved to a high risk of contamination and of breathing contaminated air. except for the head and neck and the hand and feet with a layer of impervious material. one has to have a full change. The compressed air line delivers its air immediately in front of the face. and make an analysis of any radiation accidents that occur. Such a suit effectively isolates the individual inside from any contamination on the surfaces or in the air. Compressed air supplied to the suit enables normal breathing during operations. As a breathing apparatus to be worn the same time. Such assistance is particularly essential when impervious clothing is being removed. as this arrangement provides plenty of air for breathing and at the same time helps to reduce the misting of the transparent head piece. shirt. Pressurized Clothing This is suit made of impervious material which completely encloses the individual. dose rate. which is sufficient to cause radiation induced skin injury (Fig. The risk of deterministic and stochastic effects of radiation exposure varies for different areas of the skin. patient age. The two patients received very high doses to the skin of their back. fractionation of dose. Interventional radiology finds application in Cardiology. If areas of the skin are likely to be exposed to levels of absorbed doses that approach the skin tolerance. and Neuro- radiology. and dermal fibrosis.000 procedures are carried out / year globally and more than 70 injuries have been reported.6). (ii) multiple use of radiography. 11. All relevant parameters should be documented for all interventional procedures. 294 . requiring amputation. The age of the patient. It is essential to differentiate between interventional procedures in adults. mode of operation. Six of these incidents were associated with teletherapy units. Skin injuries have been reported in patients undergone prolonged fluoroscopy guided interventional procedures such as percutaneous transluminal coronary angioplasty (PTCA). in young adults and in children. Two incidents were reported with x-ray fluoroscopy. About 700. The cumulative skin doses in some patients may exceed 10Gy. Interventional radiology using fluoroscopy equipment for image guidance may pose greater risk of X-ray induced injuries. General radiology.These injuries may appear only after a threshold period of several months. radiofrequency cardiac catheter ablation. undergoing long fluoroscopic time of imaging is also an important factor. the patient should be informed in advance about the possible effects of treatment. This breathing set may be used in conjunction with the fully protective impervious clothing and. Fluoroscopy exposure may leads to deterministic effects. vascular embolization etc. due to which 24 persons received low radiation doses and one person received a high dose on hand. skin ulcer. the individual concerned can enter a contaminated atmosphere under emergency or maintenance conditions. that includes erythema. But these effects vary with fluoroscopy time. (iii) relatively high radiation exposure for both patients and personnel. during cardiac catheterization and pace maker insertion. Regulating valves attached to the cylinders enable the wearer to control his air supply. and site of exposure. Textbook of Radiological Safety attached to a cylinder. temporary epilation. DIAGNOSTIC RADIOLOGY-SKIN INJURIES In India eight incidents have been reported in medical applications. The reason for higher risk includes (i) more extended periods of time. The most common interventional procedures like PTCA and percutaneous translumunal angioplasty (PTA) are used in patient population over 40 years of age. Small numbers of adults and children are also treated using interventional procedures.1 to 11. so desired. and telangiectasia (poikiloderma) (For color version see plate 6) 295 . July 2001) (For color version see plate 5) Fig.3: A 75 year old woman with 90% stenosis of right coronary artery. 11.5 cm hyperpigmented plaque with hyperkeratosis below right axilla (For color version see plate 5) Fig. Radiation Emergency Figs 11. tissue necrosis 5 months after procedure (B). 11. Photograph of right postero-lateral chest wall at 10 weeks after percutaneous transluminal coronary angioplasty shows 12 × 6. Photographs show sharply demarcated erythema above right elbow at 3 weeks after radiofrequency cardiac catheter ablation (A). (AJR:177.1A to C: A 49 year old woman with 8 year history of refractory supraventricular tachycardia A–C.2: 56 year old man with obstructing lesion of right coronary artery.5 months (C). and deep ulceration with exposure of the humerus at 6.and hypopigmentation. Photograph of right lateral chest obtained 10 months after percutaneous transluminal coronary angioplasty shows area of hyper. skin atrophy. Risk of breast cancer is increased (For color version see plate 7) Fig. Induration resulted in limited movement of right arm. Wound is very painful. (C) Wound has progressed in size and depth at 10 months. July 2001) (For color version see plate 7) . Disfigurement is 296 permanent. (B) Small blisters developed at 7.5: A 17 year old girl with history of cardiac arrhythmia underwent two cardiac ablation procedures in 13 months. Photographs show progression of ulceration. at 22 months. Textbook of Radiological Safety Fig. (D) Nonhealing ulcer with exposure of deep tissues.4: Skin necrosis (erythema and hyper-pigmentation).11. 11. Photograph taken 2 years after last intervention shows atrophic indurated plaque with skin telangi- ectasia at right lateral chest wall involving posterolateral aspect of breast. musculocutaneous skin grafting was performed.6: A 49 year old man with history of liver cirrhosis and intractable upper gastrointestinal bleeding who underwent two transjugular intrahepatic portosystemic shunt (TIPS) placements and one attempted TIPS placement within a week.and hyperpigmentation 6 months later. including spinous process of vertebra.(AJR:177. (A) Secondary ulceration with surrounding rings of de. 3 years after angioplasty examination (For color version see plate 6) Fig. (E) At 23 months. 11.5 months after procedure. 17 Gy whole body dose to the infant.instead of 740 MBq of Tc-99m for bone scan study. but the personnel clothing were not checked for activity. The prepardness and procedures to meet such emergencies are discussed below: 297 . A dose of 0. Radiation Emergency NUCLEAR MEDICINE: RADIATION ACCIDENTS The IAEA report 17 (2000) has reported 7 accidents in the case of unsealed sources. 50% of the prescribed dose. The lung disease patient was administered with I-31 of 370 MBq activity. The scan indicated an unusual high breast uptake of I-13l. Among the two patients. administration of 180 MBq of I-131 for a whole body scan. The supplier sent a capsule containing 444 MBq. In another event a therapy dose of 7400 MBq was administered to an 87 year old patient. In another event a patient was to be administered with 259 MBq of I- 131. Both the physician and technologists have failed to confirm that the patient was not breast feeding. to insert pacemaker etc.There were two capsule of 130 MBq each in the vial. with identical name were there. which resulted in an overdosage of 20%. When the vial is inverted only one capsule fell out and the same was administered. In another event a patient was prescribed 370 MBq for a thyroid treatment. A therapeutic dose of 370 MBq was prescribed to a wrong patient because two patients had the same name. which were labeled correctly. After 34 hours the patient experienced cardiac failure and 16 staff members attempted to resuscitate the patient. That is patient was given 130 MBq instead of 259 MBq acitivity. The technician with out reading the labels picked up two vials containing 6475 MBq and 5180 MBq of I-131 and administered both the activity to the patient. The patient was administered with 444 MBq. Though the technician calibrated the dose. A capsule containing 370 MBq was ordered. In another event a patient came for a diagnostic bone scan was administered with 333 MBq of I-131. but misread the activity of 444 as 370 MBq. Radiation Emergencies in Radioisotope Laboratory Radiation emergencies in radioisotope laboratory would normally involve only spillage of radioactive liquids. one for iodine administration and other for treatment of a lung disease. The physician familiar with the patient was not available and another physician was assigned to administer the dose. In another event a 60 year old women was referred to the nuclear medicine for thyroid ablation. which resulted a 300 Gy thyroid dose and 0.3 Gy was reported in one of the nursing staff. Another event includes. Blood and urine contaminated with radioactivity were spilled. to a feeding mother. The physician prescribed 6475 MBq of I-131 by oral administration. immediate steps should be taken to remove the laboratory coats or outer garments and to leave them in the contaminated area. used and disposed should be maintained. 4. must be kept in ready access. A proper inventory of radioisotopes received. Charts detailing various steps to be taken by the radiation workers in case of emergency should be conspicuously displayed in the laboratory. 3. Ready availability of a decontamination kit containing all the items of decontamination should be ensured to deal with an accidental spill effectively. spillage of radioactivity is the most likely accident in radioisotope laboratory. The ventilation system of the radioisotope laboratory should be routinely checked and maintained properly. the surface should be washed with damp-not wet-paper towels held by forceps. forceps etc. by droping paper towels or other absorbent material into it. If internal contamination has taken place. 4. After as much contamination as possible has been removed in this way. which require the following procedures to be recommended in dealing with such emergencies: 1. under expert medical supervision. shoe covers and a surgical face mask if available. 298 rather than away from it. 2. However. if facilities are available. should be carried out to confirm internal contamination. Confine the spill immediately. 2. Contaminated area should be decontaminated by experienced persons wearing surgical gloves. If the spilled material has splashed on to a person or clothing. Textbook of Radiological Safety Emergency Preparedness 1. Emergency Procedures It is very difficult to make rules to manage variety of radiation accidents.Handling equipment such as tongs. always working towards the centre of contaminated area. Tongs or forceps should be used to remove the contamination by absorbent material. . 5. Care should be taken not to abrade or inflame the skin surface. The absorbent material so collected should be kept in a polythene bag to be treated as radioactive waste. Evacuate the immediate area so that persons will not walk over the spill and spread the contamination. Bioassay or whole body counting. immediate action should be taken to minimize the deposit of radioactivity in internal organs and tissue and enhance the excretion of the ingested radioactive material. Hands and other contaminated areas on the body should be washed thoroughly with soap and water. 3. All radiation monitoring and measuring instruments should be routinely checked and kept in working condition. should be kept in a polythene bag for decay or ultimate disposal as radioactive waste. 1. Radiation Emergency 5. A flask that has been tipped over should be uprighted. so that the instrument does not become contaminated when the decontamination procedure is over. A room with heavy air contamination can be decontaminated from with in by drawing air of the room through an appropriate filler. Individuals outside the immediate area should be warned so that they do not enter it. For effective management of any kind of radiation emergency. Doors should be closed to prevent the escape of airborne radioactivity. – To contain. without risking themselves. the RSO should educate and familiarize all radiation workers with the steps to be taken to meet the emergency. Absorbent pads should be thrown over a liquid spill. The forceps / tongs should be kept separately covered in polythene bag for decay of radioactivity in it. In case of a large release of radioactive powder or aerosol in a room. shoe covers etc. activity involved etc. The contamination monitor should be operated by someone who is not involved in the clean up. Procedures for Handling Spills Accidental spills of radioactive materials are quite common in nuclear medicine departments. but they are not life threatening hazards. The laboratory personnel should attempt to control the spill to prevent further spread of contamination. The steps involved in the radioactive spill are: – To inform. such a room must be immediately isolated from its surroundings by shutting off mechanical ventilation and by closing windows and doors. Hence spills should be treated as events completely with out hazard and the staff should aware of the procedures to be followed. good work practice and a well controlled programme for the disposal of radioactive waste. Individuals in the immediate work area should be informed that the spill has occurred so that they can avoid contamination if possible. 2. A contamination monitor should be used to monitor the area as well as personnel during the procedure of decontamination. 6. Maintain complete records of the accident giving details of the radioisotope. Use of radionuclides in research applications will not give significant exposure to general public. 7. and – To decontaminate. provided certain basic precautions are taken. and follow up procedures. The contaminated gloves. The RSO should be informed so that he /she may begin supervising further action as soon as possible. The spill area should be closed off to 299 . These precautions mainly involve good accuracy for the radionuclides. Out of 92. contaminated individuals should not be allowed to leave the area until they are decontaminated. Personnel monitoring for contamination should be started as soon as possible. If complete decontamination is not possible. If the work surfaces and floors are constructed from a non absorbent material. Contaminated areas should be cleaned “from outside in” to minimize the spread of contamination. it continues to be in the “ON” position even after the termination of the set treatment. or only partially. Special attention should be given to open wounds and contamination around the eyes. . the International atomic energy Agency (IAEA) published its report No 17 “Lessons learned from accidental exposures in Radiotherapy”. a shower bath may be required to remove more widely distributed contamination. In the case of telegamma units. To prevent further spread of radioactivity. nose and mouth. Personnel involved in decontamination procedures should wear protective clothing to avoid becoming contaminated themselves in the process. Porous or cracked surfaces may create difficult problems. The uncontaminated individuals should not be allowed to enter the spill area. it may be necessary to cover and shield the affected surfaces or perhaps even to remove and replace them. Contaminated clothing should be removed and placed in plastic bags for storage. etc. patients or public. followed by decontamination of work areas. 3. go back to OFF position. It described 92 accidents resulting in an incorrect dose to the patient. After major localized areas of personnel contamination have been attended to. Personnel decontamination procedures should receive first priority. if it could result in higher actual or potential radiation doses than those in normal situations to personnel. It is advisable that each laboratory have on hand a thin window GM counter survey meter for handling such situations. Textbook of Radiological Safety prevent entry. soap and water is generally used for decontamination. Contamination monitoring should be done using a sensitive radiation monitoring instrument appropriate for the type of radioactivity involved. 300 ii. in other words. Contaminated skin should be flushed thoroughly with water. so that contamination and uncontaminated persons can be segregated. 32 of these accidents were related to the use of sealed sources (brachytherapy). The source does not. Decontamination of laboratory and work areas should not be attempted except under the supervision of RSO. The source falls off from the source head. RADIOTHERAPY: RADIATION EMERGENCIES A situation in a beam therapy facility can be considered as an emergency. two potentially hazardous situations may arise: i. In 2000. especially by persons who might not be aware of the spill. Later. Here the source is stationary and shielded in “OFF” position by mercury between the source and the collimator. thus leaving the source in the “ON” position even after the set treatment time is over. recently a few cases of computer software mix-up. The source was unloaded and the shutter were removed and examined. resulting in the wrong selection of electron mode. Small mass of mercury started leaking from this reservoir when the source was “ON”. The emergency situation continues until the source is completely shielded by mechanical manual or other means. Based on chromosome aberration test reports. the film badges worn by the radiation therapist. The following paragraph discusses several instance of such emergency situations in teletherapy units which have occurred in this country and abroad. The leakage of mercury was noted and they arranged to collect the leaking mercury and put it back into the unit as immediate remedial measure. But some quantity of mercury was lost in this process and hence the efficiency of mercury as the shield was gradually reduced. ranging from 20 to 50 rem were estimated to have been caused by this emergency. However. completely prevented the leakage of mercury. The shutter mechanism was working only when the unit was pointed downwards. On investigation it was noted that this was caused by an emergency situation of an Eldorado A Unit 2. A number of overexposures to personnel were reported during this period. and (iii) drum to rotate. This process continued until December 23. In medical accelerators. when the treatment by the unit had to be discontinued for want of spare parts. 1980. When the source is made “ON” the mercury is pumped out and stored in a reservoir and held there against gravity. the individual equivalent dose. to bring the source back to “OFF” position at the end of the set treatment time. which when incorporated into the unit. the hospital staff developed a special filter. the shutter used to remain partially open during the “OFF” position. the physicist and the technologist of a hospital recorded high doses. Radiation Emergency The type of situations where the telegamma source continues to be in the “ON” position. In certain systems emergency may caused by leakage of mercury which functions as a shield. The mobile shutters were encountering the obstructions on its path and as a result. They include failure of (i) pneumatic system (ii) shutter to close. In July 1984 a case of malfunctioning of the mobile shutter of a Theratron- B unit was reported. It was observed that the mobile 301 . Emergency Situations Leakage of Mercury (Shutter) In September 1980. Failure of Shutter Movement 1. have been reported. vary with the source “ON-OFF” mechanism in the unit. normally such type of emergency does not occur. the drawer and its passage area thoroughly cleaned and the source replaced. It was ascertained that the shutter mechanism had developed extraordinary friction due to damage in the ball bearing movement system. The service engineers reported that the source had to be unloaded prior to shutter repair. the shutter failed to close at the end of the set treatment time in October. Textbook of Radiological Safety shutter had lost its integrity and that a tiny particle removed from it got embedded in the housing and caused the obstruction. 1985 the shutter of a Gammatron unit remained in open position and could not be closed. 1986. Pneumatic System Failure Recently. polished and lubricated and the unit re commissioned. The personnel dose during the repair was less than 10 mrem. the source drawer did not return to the parking position at the end of the set treatment time. and the sources were pushed back to “OFF” position manually with the T-rod. the unit could not be used for treatment for about 16 months. 302 . The shutter was thoroughly cleaned. two cases of source “stuck” in the “ON” position for Gammarex- R unit have been reported. 1984. In another emergency on November 23. to be imported. In both cases. subsequently the source was unloaded. The shutter mechanism of a Gammatron unit. 1987 and the unit was repaired. Improper Functioning of Timer A typical case of improper functioning of the timer of Picker unit has been reported. 1985. This resulted in the source to be in the “ON” position continuously until the timer was manually interrupted. The service engineers reported that the shutter developed extraordinary friction. 2. Treatment was stopped until April 16. In one case. 1985. 4. serviced during the source replacement on December 13. The timer was observed to reset the time automatically at the end of the set treatment time. For want of spare parts. During this emergency the doses to personnel involved in the repair work were negligible. Even though such an incident has not been reported in India. when the source was unloaded and shutter repaired. a formal intimation regarding this malfunction was sent to all users of Picker unit. It was confirmed that the timers in the Picker units in India were functioning properly. The patient was immediately removed and defect was rectified by the hospital engineer. The individual doses received by personnel during the repair were less than 10 mrem. In another case of Gammatron unit. failed to function and remained open at the end of set treatment time on January 23. 3. The source was unloaded on April14. even manually. Personnel exposure were well within permissible levels. The treatment was abruptly terminated after one second with the patient writhing in pain calling for help from inside treatment room. Panama in May 2001.S. Corrective action plan was amended accordingly. Out of the 115 patients 42 died and 73 were alive. The IAEA team visited the place on May 22. Another similar incident from a different hospital using the same model of accelerator occurred on January 17.in which 28 patients undergoing radiotherapy in cobalt unit were affected. 1987. The radiation exposure was a major factor for death in 3 patients and partial in 4 patients. with “Malfunction-54” occurring in both the cases. About 115 patients who were treated for neoplasm by radiotherapy were affected. 1986. A third case with the same accelerator which occurred on April 25. 2001 and reported that out of 28. The “Malfunction-54” occurred when the technician inadvertently selected photon beam mode for a patient who was to be treated with electron beam of lower energy. This miscalculation resulted administration of higher doses to the patients than prescribed. The computer displayed the electron beam mode and the “beam ON” command was given to start the treatment. The death of five is due to radiation 303 .A. U.when a Cobalt-60 source was replaced. though the reported malfunction was of a different nature. AECL subsequently informed all Therac-25 users to suspend the use of this accelerator. Costa Rica A radiotherapy overexposure occurred at the San Juan de Dios Hospital in San jose. The physicist later simulated the malfunction and measured the dose in water phantom as 25000 rads in one second. A plan for correcting the errant software was submitted by AECL to Food and Drugs Administration. The operator realizing the mistake promptly corrected for the mode using the edit-key facility. In the meantime the fourth incident occurred where although the photon beam mode was selected the heavy metal target did not come into position into the path of the electron beam and instead a light field mirror came in position to intercept the electron beam. and an error was made in calculating the dose rate. Panama Accident A radiation accident occurred in the National institute of oncology. The first two patients died and the third patient was seriously maimed. The event occurred on August 22. San Jose. the new source was calibrated. After the source loading.eight patients had died.1996. 1985 was reported later. Costa Rica in august and September 1996. Radiation Emergency Software Mix-up in Accelerator Two incidents of massive overdoses of patients took place in a hospital in USA from Therac-25 accelerator on March 21 and April 11. The spatial coordinates of the shielding block has to be fed into the TPS in way that one shield at time. They received a whole body equivalent dose of 135 mSv and 0. received significant overexposure. which resulted incorrect dose and treatment times. the source drawer momentarily came out of the transfer flask before the worker pushed back. was followed by an error at the time of recommissioning.org). Lack of written procedures and manual check when the data input procedure was changed. resulted radiation overexposure to the above patients. Overexposure During Source Exchange Two radiation workers. Patients were under dosed to a maximum of 17 %. The facility and the radiation safety officer must be prepared to meet such kinds of emergencies at any time. serious accidents can take place unless proper care is taken. When the tool was pulled out. Line of action to be followed may vary with the type of emergency and the personnel must be clearly aware of the same Radiation Emergencies-Fall of Source Drawer During source replacement or source head repair of telegamma therapy units with source “ON-OFF” mechanism. no conclusion was made. The error was reflected as incorrect output tables for all 4 beam qualities and for all field sizes other than 10 x 10 cm2.7 mSv respectively. Ottawa Hospital Cancer Center A relocation of an orthovoltage treatment unit from one campus to the other in the Ottawa hospital cancer centre in the Fall 2004. No overexposure was reported and the cause was due to the omission of a back scatter conversion factor for all the fields other than 10 x 10 cm2 (www. A total of 1019 patient treatments were delivered to 620 patients using the incorrect orthovoltage output tables during November 2004 to November 2007. 2008 it was found that one of the fingers of the individual was blistering. The extremity dose was estimated as 25 Sv. Different types and degrees of emergency as discussed above can potentially occur in beam therapy facilities. Later on August 15. Recently. Textbook of Radiological Safety over exposure. The workers transferred the source drawer from the unit head to the transfer cask with the help of tool.iaea. two such serious accidents 304 have taken place in India in two different institutions. From August 2000. sources . one death is related to cancer and remaining two death. The cause for the accident due to wrong data entry into the treatment planning system (TPS) computer. Brazil on july 21. the coordinates of the all the shielding blocks were entered as a single block. In each case. while working on a source exchange of a decayed cobalt-60 source in a hospital in the state of Sao Paulo. 2008. 50 mSv (2950 mrem) and 12. 1. In one case. Source Retrieval Operation The retrieval operation was planned on the basis of information collected during a preliminary visit to assess the situation.40 mSv (1240 mrem). Temporary extra shielding was planned for secondary walls to be provided by piling up sand bags upto 1 meter height. it was cobale-60 source of 6000 RHM and in the other it was Caecium-137 source of 2050 Ci. Radiation Emergency loaded in parallopiped shape source drawer fell down from the source head during repairing of shutter mechanism. 11. Realizing the seriousness of the situation. An aluminium tray with a groove like depression at the bottom to sit on the source drawer (Fig. which was lying freely in the cavity slipped down from the head. They received whole body equivalent dose of 29.7) was designed and fabricated. They removed the gear box mounted at the back side of the drum shutter to look for any foreign particles obstructing the movement. 11. The details available from the layout of the installation were also useful in planning the management of the accident. Fig. Later they removed the front plate as well as the arresting strip of the drawer. they came out and locked the room immediately.7: Aluminium tray designed to cover the source drawer Area monitoring of the entrance to the treatment area and other areas of interest were carried out using a Teleflex cable of 12 m length 305 . The source drawer. First Incident: The first incident took place when two under trained- staff members of the institution tried to repair the shutter mechanism of a Gammatron-3 teletherapy unit. The head was tilted through +300 in the forward direction and the unit was rotated to bring it to a convenient position. It was planned to cover the source drawer with the above tray and to fill it up with lead shots through a polystyrene pipe by personnel positioned behind the maze wall. which was locked to the ground. a mirror mounted on a wheel trolley was employed at the entrance of the treatment room to locate the source drawer. After emptying . In the wall common to control room and treatment room. The source drawer was lying at the middle the platform. All unwanted materials and a major portion of the wooden platform inside the room were quickly removed. A rehearsal of the operation with a dummy drawer was conducted in the adjacent teletherapy room. The various location in which radiations were measured are given in Fig 11. the drawer hade to be brought to the edge of the platform. With the help of this mirror.0 m length and that the equivalent dose for this operation will be about 15 mSv (1500 mrem). this job could be carried out with an equivalent dose of 12.1. positioning the aluminium tray to cover the source drawer and to fill it up with lead shorts were not viable to persons positioned behind the temporary shielding erected at the entrance position. About 350 Kg of lead shorts of diameter 1-2 mm were poured into the aluminium tray through this pipe. The source drawer was lying on this platform. The exposure rate at the drilling position was then reduced to 5 mR/h from 200 mR /h. which was covering the source drawer. The source drawer 306 was then transferred to the groove of the second tray. To transfer the drawer into a transport flask. Lead shots (about 40 Kg) packed in cloth bags were used for this purpose. Actually. it was observed that the major length of the source drawer was hidden by the base drum of the couch. a tapered hole was drilled at the height of 2. This brought down the radiation level inside the treatment room to a workable level. temporarily.5 mSv (1250 mrem) to the operator. a raised wooden platform made of interlocked portions was provided in the room for the convenience of patients as it lowered the height of the couch. It was concluded that aluminum tray can be placed over the source drawer by one person entering the room with a remote handling tong of 2. keeping the meter of the monitoring instrument outside the room.5 manrem). This was carried out for a collective equivalent dose of 0. Since there was no lead glass viewing window and since the CCTV was focused to the couch. Further. The radiation levels at various points measured before and after providing temporary shielding are given in table 11.025 mansievert (2.8. Another aluminium tray of slightly larger size and smaller grove for source drawer to exactly fit in (to reduce streaming) was fabricated and positioned in line with the aluminum tray with lead shots in it. Polystyrene pipes of 5 cm in diameter and 6 meter in length were extended to the aluminium tray through the hole drilled on the wall at Control room. As such. Textbook of Radiological Safety connected to the detector.5 m from the floor for the passage of polystyrene pipe to facilitate filling up of the aluminum tray had to be shielded. The total collective equivalent dose was about 0.70 × 103 1 2. it was used in line with the second tray for shifting the source drawer further close to the edge of the platform to enable it to be loaded into the transportation flask. The locations where radiation levels were measured are numbered and marked in Fig.31 150 7.50 5 × 103 5. Table 11.04 4 11.07 man sievert (7.02 2 8.22 600 8. The source was facing the ceiling. Entrance to 43. who missed to arrest the source drawer.1.97 800 1.17 20 0.44 50 4 0.44 50 0. Radiation Emergency the first tray.11. Control panel 0.35 40 maze wall 2.00 60 × 103 9.1: Radiation levels in and around the Telecobalt facility before and after providing temporary shielding at the entrance and maze region (The source drawer with 60Co source of 222 TBq (6. Door 0.87 100 3.000 Ci) was lying on the wooden platform inside the treatment room. 1.87 100 0. Second incident: In this case a source drawer containing 2050 Ci Caesium- 137 fell down during repairing of the shutter mechanism of a Ceasa - Gammatron unit by the service engineers.74 200 0. the teletherapy unit was repaired and subsequently the source loading was carried out.8) Radiation levels in and around the Telecobalt facility Before providing After providing temporary shielding temporary shielding Location Location Air kerma Exposure Air kerma Exposure number description rate (mGy h-1 ) rate (mR h-1) rate (mGy h-1) rate. 0. The second tray was filled . Retrieval operation The radiation levels in the control room and surrounding areas were not very high and operation of retrieval could be managed from the entrance door.74 200 1. 104. treat room 522.87 100 0.50 5 × 103 10.40 12 × 103 43. 0. Behind the 1. The equivalent doses received by personnel involved in the retrieval operation are given in Table 11.(mR h-1) 1. shielded source drawer had to be lifted through 20 cm to bring the source drawer in line with the cavity loading the fallen source drawer into transportation flask.87 100 5.0 man rem).74 200 6. Before loading source drawer into the transportation flask. The fallen source drawer was covered by an aluminium tray and it was filled with lead shots. A second compact tray of mild steel mounted on a mild steel plate with three hooks on each side was fabricated and 307 placed in line with the first aluminium tray. 6.00 60 × 103 522. dose calculation or the quantities and units resulted in doses that were up to 170% of the prescribed dose. The total collective equivalent dose in the operation was about 0. the use of an incorrect source due to fading of the color coding. serious accidents involving high exposure to personnel and long down time of machine can take place.8: Lay out of the teletherapy facility. skillful planning of management of accident is necessary for keeping radiation dose to the minimum to personnel involved in the operation. 308 Some accidents were related to human mistakes. This is listed under . Additional shielding by interlocking lead bricks were provided on three sides and on the top of the tray and the trolley was positioned in a corner of the room. Plate).The type and number of accidents is summarized in the Table 11.S. presents 32 accidents related to Brachytherapy . Textbook of Radiological Safety Fig. BRACHYTHERAPY: RADIATION ACCIDENTS The IAEA report No 17. 11.2. Later the source drawer was loaded into the teletherapy head after the repair of the unit. From the above incidents we can conclude that unless proper care is taken during servicing or source loading. By using chain pulley system the source drawer shielded under the mild steel tray and resting on the mild steel plate was lifted and placed on a trolley which was provided with 10 cm thick layers of interlocking lead bricks covering the entire base of the mild steel tray. In addition.02 mansievert (2 manrem). where radiation levels are measured with lead bricks and lead shots and source drawer was transferred below this tray (on the M. for example. Errors in the specification of the source activity. hypopharynx received 35 Gy and the target received only 1 Gy. The error was not discovered until the treatment was over. Table 11. Because of this error. The other events includes using a HDR prescription for the wrong patient. Over all the treatment delivery errors can be summarized as follows: positioning of the active source train outside the treatment volume. The safety assessment will identify accident scenarios and situations. IAEA reported that the misadministration is due to malfunctioning equipment. There is a written documentation of rules for . the realization of the clinical intent of the radiation oncologist. Radiation Emergency “other” in the table. In one HDR event the patient was prescribed a dose of 35 Gy to lung. and counter measures for mitigation are designed. and malfunction of the HDR equipment etc. mispositioning of dose prescription points and failure to detect a source that separated from its cable and remained in the implanted catheter for 91 hours. To achieve this personnel need to be trained and simulation drills carried out. which also includes accidents caused by badly implanted sources. The above demonstrates the need for a well designed programme of quality assurance in any Brachytherapy department. such as catheters do not allow full movement of sources.2: Type and number of accidents reported in Brachytherapy treatments (IAEA 2000) Accident caused by Number of cases Dose calculation error 6 Error in quantities and units 2 Incorrect source strength 7 Equipment failure 4 Other 13 Total 32 HDR Brachytherapy units have higher potential for damage to patients as a result of misadministration. with out hesitation or mistakes. accidents or un usual events may occur. The most severe accident was due to equipment failure. Some of the actions in the emergency response plan need to be taken immediately. removal of the sources by the patient or otherwise dislodged sources. EMERGENCY PREPAREDNESS: ACTIONS In spite of preventive measures. There was a kink in the catheter which positioned the source 26 cm away from the target site. Its goal should be the consistency of the administration of each individual treatment. where a lethal dose was delivered to a patient. A clear and concise list of actions and responsible officers 309 is posted in relevant places. It also mentioned the inadequacy of personnel training which caused the misadministration. and the safe execution of the treatment with regard to the patient and staff. If this procedure does not result in returning the source to the “OFF” position. the technician must remove the patient without himselft getting directly exposed to the primary beam. calibrated and working. pressing a popped-up button on the source head. This may involve procedure such as pushing the source drawer to the parking position with a T-rod. not to expose any part of their body including hands. or by switching off electric power as specifically directed in the Instruction Manual supplied by the manufacturer. To facilitate such action. It must be possible to procure . This would also imply that an audio- type gamma zone monitor is available. Restoring the Source to “OFF” Position The RSO must try to return the source to the “OFF” position as specified for the unit concerned and with appropriate care. of these persons must be conspicuously displayed. Requirement of Equipments and Accessories The follow up materials and equipments must be available in the hospital 310 and be kept outside the telegamma room. Administrative action will include vacating for shielding adjacent rooms and areas and cordoning off the facility as required. rotating a wheel in the gantry. in the case of any emergency. including simulating exercises. the RSO must leave the treatment room. After the patient is removed. which needs to be periodically reviewed. to the primary beam. if any. Source not Returning to “OFF” Position Removal of the Patient If the source does not return to “OFF” position after the set treatment time is over. It must be clearly demonstrated to the staff that the dose equivalent to the worker for such a procedure will be only of the order of 10-20 mrem. Line of Command of Actions The RSO must establish the line of command of actions to be taken. Textbook of Radiological Safety action and training. and wait for further instruction. for the emergency response plan. The room must be closed immediately and the service engineers of the company concerned may be summoned for appropriate assistance. They must also be told to be in the treatment room only for the minimum time required and. the technician must lock the room. inform the RSO immediately. the RSO must routinely advise the workers regarding the route to be taken by them inside the treatment room for various directions of primary beam. which will indicate that the source is “ON” or “OFF”. in any case. The addresses and telephone numbers. This will include the type of immediate action to be taken and persons to be contacted. must be kept at easy accesses. if it has fallen down. A wide range survey meter with long cable facility is desirable. Sand bags: Generally. 6. 8. Lead shots: 300-400 kilograms of small sized lead shots. Long pipe and funnel: A long pipe is needed so that the lead shots can be dropped through a funnel connected to one end kept near the door or maze in such a way that radiation is avoided by the worker to the extent possible. and in some cases. Transport container: The transport container (source flask) must be available locally with the servicing firm. etc. The pipe must be in an inclined position. for primary wall too. Binoculars: Binoculars could be of help to verify whether the source is in the “ON” or “OFF” position. It must also be 311 . Long handled tongs: Long handled tongs on which the radiation probes could be fixed will be needed to monitor the radiation levels at various locations in the telegamma room. once the lead shots and lead wool are thrown to cover the source. Lead bricks: Several lead bricks of standard size. A number of sand bags may need to be arranged on these walls. so that the source can be initially shielded. so that the exposure rates outside are within permissible levels. all walls become primary walls. However. at very short notice in case of emergency. regular and interlocking type. additional shielding may be needed for the secondary walls. will be useful to shield the source further. Survey meter: Properly calibrated and maintained survey meters of appropriate ranges must be available at all ranges. 10. lead shots. of about 1-2 mm diameter. This will help in deciding the course of action to be followed. 1. so that remedial action can be initiated immediately in the case of the source fall. This will be needed to shield the source in case it falls off from the unit. depending on the location in the room where the source has fallen. a telegamma-particularly telecobalt-room is designed such that two walls will act as primary walls and the remaining two as secondary walls. 5. This will enable personnel to approach closer to the source for the retrieval work. 4. 11. 2. 9. as also its location. before its actual retrieval. 3. T-rod: T-rod or other such equipment meant for the unit. if the source falls on the floor. in such a way that the other end is over the source. Radiation Emergency items such as sand bags. Hence. 7. In one of the recent major incidents the instruction manual was located only a after prolonged search. Lead wool: Several kilograms of lead wool preferably packed in bags will be needed to be thrown over the source from a safe distance. Manual: Operation/service manual of the unit which will give details regarding type of source drawer etc. In many cases. AERB. of any accident or potentially hazardous situation that may come to his notice. Prevention of Emergency Generally. It is the duty of the radiological safety officer to investigate and initiate prompt and suitable remedial measures in respect of any situation including emergencies that could lead to radiation hazards. MUMBAI. drawer or shutter. emergencies arise in the case of old and poorly maintained units. Radiological safety division. within 24 hours. It must be pointed out that most of the major incidents involving telegamma units have occurred during source transfer or repair work. if needed. The employer shall inform the competent authority. of any accident involving a source or loss of source of which he is a custodian. dose received and steps taken to avoid such emergencies in future. This will also help to avoid tendency for complacency among the staff. The licensee shall prepare emergency response plans and submit to the competent authority for approval. 312 . The report should give details of the incident. as well as regular servicing. These should never be resorted to. Personnel monitoring dosimeters: All personnel in the telegamma room including casual workers must wear personnel monitoring dosimeters. He should develop suitable emergency response plans to deal with accidents and maintaining emergency preparedness. including the causes. Legal and Regulatory Requirements Rule 20 of Atomic Energy (Radiation protection) rules. 12. It must be stressed that proper work discipline. remedial action. It must be ensured that any servicing of the source head must be done only by experienced engineers and in the presence of the RSO. The RSO must send a report of the emergency to the Head. Periodic drills must be arranged by the RSO to simulate emergency situations. simple requirements of radiation safety. The worker shall inform the licensee and RSO. Typical example include arrestor not provided to prevent movement of source drawer and transport container not immobilized during source transfer operation. maintenance and quality assurance tests of the teletherapy unit and associated equipment will definitely help to prevent potential emergencies. 2004 stipulates that the employer is the custodian of radiation sources in his possession and shall ensure physical security of the sources at all times. Textbook of Radiological Safety stressed that in case of major repairs of the head. the source. emergencies arise because of temptations to compromise on or by-pass of. must be unloaded prior to such work. legs and face are irradiated but any other part of the body may also be involved. Skin Effects Following Exposure Transient Erythema Early transient erythema may occur in a matter of hours following doses of more than 2 Gy. because of changes in permeability of capillaries. a small part of the body is exposed to radiation. feet. It is the dose to these cells that determines the severity of skin damage. Damage to the germinal cells in the basal layer is critical in the pathogenesis of erythema and desquamation. The main wave of erythema peaks at 10 days to 2 weeks and requires a larger dose of about 6 Gy. moist desquamation and ultimately necrosis of the epidermis result. sebaceous glands and hair follicles. atrophy of dermis. fibrosis of dermis and increased susceptibility to trauma and chronic ulceration. Dry Desquamation Dryoeneum. sweat glands. This is followed 2-4 weeks later by fixed erythema which may come in waves is much deeper and more prolonged than the transient erythema. Most commonly. Radiation Emergency MEDICAL MANAGEMENT OF PERSONNEL EXPOSED TO RADIATION Partial Body Exposures – Localized Exposure (Radiation Burns) In localized exposure. Epilation is permanent if the dose exceeds about 7 Gy. Temporary epilation may occur after doses of about 3 Gy. much like a sun burn. Long term sequelae are pigmentation. Healing requires the repopulation of basal cells from surviving clonogens. The earliest damage seen in transient erythema which comes immediately after exposure and is due to dilation of capillaries resulting from histamine like substances released by injured cells. may occur after single doses of more than 14 Gy. If the dose is more than 3Gy (300 rad) epilation. because of depopulation of clonogenic cells in the epidermis. with an on set at about 3 weeks and regrowth requiring 5 weeks or more. dry. Some of the radiation effects and the levels at which these may occur are given below in Table 11. Skin is the first organ to be exposed following irradiation.3. hands. occurs if there is sufficient reduction in the replicative capacity of germinal cells or the matrix of the hair follicles. 313 . Epilation Epilation or hair loss. or tingling and epilation. Healing is caused by repopulation of surviving clonogens or micration of clonogenes from the edges of the irradiated area. Initial symptoms are erythema. The pain is experienced during the first few days. endothelium of blood vessels may not be obvious. they heal and clear up as the population of basal cells recovers. but provided they are not severe. which continues to progress for several months. Full Thickness Radiation Burn This is similar to third degree burns and a serious version of transepidermal injury. Pain is an important feature of the exposure of skin. Radiation burns are sometimes deceptive on superficial appearance as damage to important organs in subcutaneous tissue nerve endings. Transepidermal Burn This is similar to second degree thermal burns with a latent period of 1-2 weeks. besides subcutaneous tissues other internal structures are affected and may give rise to radiation necrosis of bone. itching. The injury extends up to the dermis and produces prompt and severe pain.3: Radiation effects and radiation dose Radiation effects Threshold dose of X and γ rays Time of onset Early transient erythema 2 Gy 2-24 h Temporary epilation 3 Gy 3 wk Dry desquamation 14 Gy 4 wk Secondary Ulceration 24 Gy 6 wk Late erythema 15 Gy 8-10 wk Ischemic dermal necrosis 18 Gy >10 wk Telangiectasis 10 Gy >52 wk Moist Desquamation Moist desquamation requires higher doses greater than 18 Gy and also results from depopulation of clonogenic cells in the epidermis. swelling. These effects may cause substantial discomfort. to high doses of radiation. sweat glands. The severity of burns depends on the dose and dose-rate and doses of 30 Gy (300 rad) or above blistering and skin loss may take place. 314 . the injury to the endothelium of blood vessels is the most serious. In such cases. the healing will take long time and surgical intervention may be required. muscle and other internal organs. hair follicles. particularly in the extremities. pain. lasting several hours and it may last for long periods. Textbook of Radiological Safety Table 11. Among these. In case damage to circulation is present. This pain is maximum with the appearance of vascular lesions. It produces endartritis obliterans. leading to necrosis of overlying tissues. Blood lymphocyte culture and Chromosomal analysis 3. 315 . Radioisotope scintigraphy 10. the nature of radiation and energy. Even after the area of burn becomes apparent. should be collected. Culture and antibiotic sensitivity test 5. Slit lamp examination of eyes 11. This information is helpful in planning any surgical intervention with out waiting for the clinical symptoms to unfold fully. Management of Radiation Burns History A detailed history of accident with name. Investigation The following investigations and procedures are recommended: 1. Physical dosimetry Samples should be taken immediately for items 1-5 in the above list. the underlying damage cannot be observed with accuracy clinically. and the functional status of the organ. Complete blood count 2. telangiectasia. along with other symptoms. age and sex of the person. These effects occur months to years after higher doses of radiation (10-18 Gy) and are caused by primarily by vascular damage to the dermis. Sperm count 4. possibility of whole body exposure or contamination etc. in which case they are referred to as consequential late effects. Serial color photography 7. Radiation Emergency Long Term Effects Long-term sequelae. The time at which transient erythema occurred. Some times the patient may not aware of irradiation and dose. Scintigraphy may be done before slit examination in view of blood contamination with 99mTC. Concurrently photographs should be taken and dosimeters sent for evaluation of dose. include dermal atropy. Thermography and scitigraphy offer a means of detecting areas affected significantly by localized irradiation. Non invasive vascular studies 9. Personal TLD badges will provide some idea about the exposure. Estimation of radionuclides in urine and stools 6. and necrosis. Late effects also may develop after unusually severe early effects. with the development of fixed erythema. Complete examination of the skin repeatedly on the first day is required to see is there any prodromal erythema. Thermography 8. will enable the physician to come to a rough conclusion regarding the dose and the ultimate prognosis. Transepidermal burn: Pain should be relieved by analgesics. Intractable pain ii. Specific Treatment 1. Textbook of Radiological Safety If there is leucopenia in the first week. BIBLIOGRAPHY 1.8 2004. Usually the burns will heal without skin grafting in the absence of infection. Larger areas involving necrosis and gangrene of distal portions of fingers of extremities will require amputation. There is danger of infection which should be treated vigorously. Lastly. A bland lotion or steroid ointment should be applied locally.tissue loss and infections. it is suggestive of whole body exposure. 3. In case there is leucopenia at 2-6 weeks. and drug like phenylbutazone. follow up of such cases is important because healed radiation burns may result in weak atrophic skin that is subject to chronic and recurrent ulceration. Degree to which vascular damage can be estimated v. 2.cm) skin grafting will be required. New Delhi 2004. 1990. 316 . Sterile protective dressings should be used. AERB safety code: Medical management of persons exposed in Radiation accidents. Systemic antibiotics should be given for prevention of infection.which cause bone marrow depression should be used. 3. No tight clothing should be worn on the affected part. early excision and skin grafting may spare the patient from pain and discomfort. The time for amputation and reconstructive surgery depends on the following determinants: i. A practical guide to quality control of Brachytherapy equipment: ESTRO Booklet No. Bone marrow depression may further complicate the condition. 2. This will require surgical intervention. giving rise to severe pain.AERB/SG/MED-1. surgical treatment should be kept at minimum until haematopoietic recovery takes place (usually in about 6-8 weeks). Degree of control over infection iv. In beta-ray burns. et al. Full thickness radiation burn: The burns may progress from initial blistering to skin loss and deep tissue necrosis. Surgical intervention should be kept to the minimum during this phase of bone marrow depression which usually lasts about 4-8 weeks. Radionuclides in Bio-Medical sciences-An introduction. the timing of which will be difficult to decide due to slow progression of burn. Foundation books Pvt. Value of the part. Mild erythema: This may become dry and start itching in 3-4 weeks. Chandrani L. In case the involved area is more than a few square cms (2-3 sq. Size and location of injury iii. Ltd. IAEA. 5. 317 . Seiber. Lecture notes: Training course on Radiation safety for Radiation therapy technologists. Safety report series No 17: Lessons learned from accidental exposures in radiotherapy. Radiation Emergency 4. AERB and RPAD. BARC. JA. RSD. Edwin ML. (2nd edn. The essential physics of medical Imaging. John MB. Jerrold TB.) Lippincott Williams and Wilkins 2002. Mumbai. 2000. 6.Vienna. transport and delivery Construction materials 84 of package 257 Consumer products 11 Brachytherapy facility design 91 Contamination control 229 Brachytherapy sources. Cell 14 munoassay (RIA) laboratory 189 Central beam alignment 122 AERB specification for layout of radio. storage. 115 Collective dose 6 Artificial sources 10 Collective effective dose equivalent 7 Assistance to patients 206 Collimator axis. Chance of approaching dose limits of therapy facility 194 exposure 226 Air conditioning 85 Chemical purity 150 Alignment of table gantry 134 Chemical treatment 271 Annual limit on intake 8 Chest and extremity radiography in Applicator integrity 160 pregnancy 222 Aprons 280 Classification of waste 269 Area monitoring 103 Cobalt-teletherapy machine survey 114 Area survey 113. Index A Brachytherapy: radiation accidents 308 Absolute risk 26 Breastfeeding 233 Absorbed dose-rad/gray 2 Breathing apparatus 281. light beam axis and Associated facility 87 cross-hairs coincidence 155 Atomic energy act-1962 167 Collimator rotation 155 Atomic energy regulatory board 167 Collimator test 135 Avoid of pregnancy after radionuclide Committed dose 6 therapy 237 Computed tomography installation 70 Avoid of pregnancy after receiving Concentrate and contain 268 radiotherapy for breast cancer Conduit 83 treatment 242 Congruence of radiation and optical fields 121 B Consent 184 BEIR report V and VII risk estimate 26 Consentee 185 Biologic effects 17 Consignor's declaration 258 Booking. equipment and Continuation of work of a pregnant installations 192 employee in X-ray department 224 . 293 Accuracy of corrections for count losses Burial of solid waste 273 143 Actions and precautions that can reduce C radiation exposure to the fetus 234 Calibration and maintenance of radiation Additional installation requirements 87 monitoring instruments 117 Additional requirements for type A Carbon fiber materials 210 packages 250 Cardiac catheterization and pregnancy Additional requirements for type B 223 packages 251 Category III-yellow 249 AERB classification of radioisotope Category II-yellow 249 laboratories 188 Category I-white 249 AERB guidelines for starting radioisotope Ceiling mounted barriers 205 laboratory 187 Ceiling 55 AERB guidelines to set up a radioim. roentgen 2 Disposal of radioactive solid waste 272 Exposure rate constant 3 Disposal of radioactive waste from nuclear medicine procedures 278 F Distance 32. D 309 Decontamination of equipment 285 Emergency procedures 291. 41 Facility design and construction 78 Doors and interlocks 80 Facility design for brachytherapy 59 Dose limits to patients 199 Facility design for diagnostic X-rays 42 Dose limits 197 Facility design for nuclear medicine 47 Dose philosophy 197 Facility design for radiotherapy 48 Dose reduction in fluoroscopy 213 Failure of shutter movement 301 Dose reduction methods in paediatric Fetus risk 28 chest CT 220 Field area 207 Dose reduction methods in pediatric Field flatness 158 abdominal CT 221 Field symmetry 158 Dose reduction methods in pediatric Film badge 96 radiography 217 Filtration 207 Dose reduction methods 219 Fissile packages 248 Dry desquamation 313 Flatness and symmetry 159 Ducts and shielding 82 Fluoroscopy installation 68 Focal spot size 122 E Focus to table top distance 134 Early somatic effects (partial body Footwear 280. 288 320 irradiation) 19 Free drop test 250 . Textbook of Radiological Safety Control of PH 151 Early somatic effects (whole body Control of starting materials 148 irradiation) 18 Controlled and uncontrolled areas 67 Effective dose or effective dose equivalent Cosmic rays 9 4 Counseling of patients 226 Effects on radiation exposure in utero Counting rate performance 139 (ICRP-84) 221 CT and pregnancy 222 Electrical and mechanical tests 145. 216 Detriment 8 Equipment 74 Diagnostic radiology-skin injuries 294 Equivalent dose 4 Dilute and disperse 268 Establishing a diagnostic X-ray facility 65 Disposal of low activity wastes into the Establishing a nuclear medicine facility environment 276 71 Disposal of P-32 and I-131 into municipal Establishing a radiotherapy facility 79 sewers by medical users 277 Evaporation 271 Disposal of radioactive effluent into the Excepted packages 247 ground 276 Exposure . 159 CT number linearity 147 Electron beam data 158 Emergency preparedness: actions 298. 298 Decontamination of personnel 282 Emergency protective clothing 293 Decontamination of protective clothing Emergency situations 301 286 Employer 183 Decontamination of working areas 283 Energy resolution 139 Decontamination procedures 281 Energy 158 Delay and decay 268 Enhanced natural sources 10 Determination of particle size 151 Epilation 313 Deterministic effect 20 Equipment and peripherals 207. 71 General precautions 240 K General radiography installation 68 Kerma 2 General requirements 249 Genetic effects 21 L Genetic risk 27 Labeling and identity 231 Genetically significant dose 7 Labeling of the package 254 GM type survey meters 106 Laboratory coat 280 Guidelines for using TLD badge 99 Late somatic effects 19 LDR and MDR treatment rooms 92 H Lead apron 204 Half value layer 35 Leakage and contamination 163 HDR brachytherapy survey 116 Leakage limits for brachytherapy 40 HDR treatment rooms 93 Leakage limits for cobalt teletherapy Head leakage source on position 114 39 Head leakage-source off condition 114 Leakage limits for X-ray housing 39 Hereditary effects 19 Leakage of mercury (shutter) 301 High contrast resolution 136 Leakage radiation 38 High contrast sensitivity 134 Legal and regulatory requirements 312 Licensing 78 I Line of command of actions 310 IDR and TADR 49 Linear accelerator 113 Image intensifier assembly leakage 134 Linear energy transfer 16 Image intensifier 211 Linearity of MA station 127 Image quality tests 146 Linearity of timer 128 Image quality-attenuation and scatter Liquid waste 270 correction accuracy 144 Long term effects 315 Image receptors 210 Low and high contrast resolution 147 Image uniformity and pixel noise 146 Low contrast resolution 136 Imaging rooms 74 Low contrast sensitivity 134 Impressive protective clothing 288 Improper functioning of timer 302 M Incineration 272 Mammography installation 69 Industrial packages 248 Management of cadavers containing Information to carriers 260 radionuclides 187 Inspection of the equipment 108 Management of radiation burns 315 Instantaneous dose rate method 52 Marking of package 253 Instruments and accessories 109 Maternal hydration 237 Interaction of radiation with tissue 14 Measurement of computed tomography Internal radionuclides 10 dose index (CTDI) 136 321 Intrinsic resolution 138 Measurement of MA linearity 136 . Index Full thickness radiation burn 314 Investigation 315 Fully impervious clothing 293 In-vitro and radioimmunoassay (RIA) 75 G In-vivo diagnostic facility 74 Gantry and couch 146 Ion exchange 271 Gantry rotation 155 Ionization chamber survey meter 104 Gantry tilt 135 Gaseous waste 275 J General checks 108 Jaw symmetry 154 General guidelines 64. 193 Natural radiation source 9 Personnel responsibilities 182. Textbook of Radiological Safety Measurement of operating potential Patient motion 211.localized Protection in fluoroscopy 212 exposure (radiation burns) 313 Protection in nuclear imaging 227 322 Particulate contamination 151 Protection in pediatric imaging 215 Patient dose reduction 229 . 193 Nuclear fuel cycle 11 Personnel safety during source transfer Nuclear medicine physician 186 operations of teletherapy and HDR Nuclear medicine technologist 186 brachytherapy units 238 Nuclear medicine: radiation accidents Personnel wear 228 297 Photon beam data 158 Pin prick method 161 O Placards 256 Occupancy factor (t) 41 Pneumatic system failure 302 Occupancy in the room 206 Pocket dosimeter 100 Occupational exposure 11 Positional accuracy 160 Ongoing evaluation of product perfor. 185. 134 Patient waste 280 Medical exposure 11 Pediatric computed tomography 218 Medical management of personnel Pediatric exposure 229 exposed to radiation 313 Pediatric fluoroscopy 218 Minimum facilities required 189 Pediatric radiography 216 Model plan 88 Penetration test 251 Moist desquamation 314 Performance evaluation of CT 145 Multiple beam alignment check 157 Periodic QA schedule 164 MTC-99 generators 280 Personnel monitoring systems and features 102 N Personnel requirements 182. 136 237 Overalls (boiler suit) 280 Pregnant woman and radiotherapy 241 Overexposure during source exchange Preparation of package for transport 304 253 Overshoes 281 Pressurized clothing 293 Prevention of emergency 312 Primary barrier adequacy 115 P Primary barriers 50 Package handling 252 Primary radiation 37 Package radiation levels 253 Procedure for authorization 190 Packaging and package requirements Procedures for handling spills 299 249 Protection in computed tomography Panama accident 303 214 Partial body exposures . 185. 217 135 Patient observation and communication Measurement of timer linearity 136 81 Mechanical isocenter 155 Patient positioning 211 Mechanical test 251. Pregnancy and radiation protection in mance 152 nuclear medicine 233 Optical and radiation beam congruence Pregnancy and radiation protection in 155 radiotherapy 240 Optically stimulated luminance dosimeter Pregnancy and radiation 221 100 Pregnant patient with cervical carcinoma Organ shield 205 242 Ottawa hospital cancer center 304 Pregnant staff and continuation of work Output consistency 128. 111 Quality assurance for computed tomo. Radiopharmacy 77 graphy 134 Radiotherapy: radiation emergencies Quality assurance for diagnostic radio. 287 Radiation survey in diagnostic radiology Rule 1. 300 logy 119 Reduction of fetal dose when a pregnant Quality assurance for nuclear medicine patient undergoes radiotherapy 137 241 Quality assurance for PET-CT 141 Regulatory controls for diagnostic X-ray Quality assurance for radiography units equipment and installations 181 120 Regulatory controls for nuclear medicine Quality assurance for radiotherapy 154 facilities 184 Quality assurance test format 129 Removal of loose contamination 284 Removal of relatively fixed contami- R nation 284 Radiation dose from patients 228 Removal of the patient 310 Radiation dose tests 136 Requirement of equipments and Radiation effects in utero 23 accessories 310 Radiation effects on DNA 22 Respirators and dust masks 287 Radiation emergencies in radioisotope Responsibility in the control of radiation laboratory 297 accidents 292 Radiation emergencies-fall of source Restoring the source to "off" position drawer 304 310 Radiation exposure level (XT or P) 41 Reverse osmosis 271 Radiation induced cancer 20 RHM and RMM 3 Radiation isocenter 156 Risk models 25 Radiation limits for shielding design Risk to a pregnant woman. 154 Protective devices 204. Short title. when a 199 family member is treated with Radiation profile width 135 radioiodine 236 Radiation protection rules-2004 168 RMM and curie 3 Radiation risk 24 Room lighting and lasers 83 Radiation safety 147 Routine protective clothing 280 Radiation sensitivity and profile Rubber boots 281 widths 146 Rubber gloves 280. QA for mammography X-ray unit 133 186 QA for radiopharmaceuticals 147 Radiologist 183 QA for single photon emission computed Radionuclide activity 148 tomography (SPECT) 140 Radionuclide purity 148 QA for treatment planning system 164 Radionuclide therapy 78. extent and 107 commencement 168 323 . 227 Radiation units 2 Radioactive fallout 11 Q Radiochemical purity 149 QA for fluoroscopy X-ray unit 134 Radiography 204 QA for gamma camera 138 Radioiodine therapy and pregnancy QA for HDR brachytherapy 159 235 QA for linear accelerator 154 Radiological safety officer (RSO) 183. Index Protection in radiography 206 Radiation survey in nuclear medicine Protection in radionuclide therapy 232 111 Protective barrier design 40 Radiation survey in radiotherapy 112 Protective clothing 286 Radiation survey 107. Restrictions on use of sources Rule 6. Source to object distance 209 radiation installations and Sources and nature of waste 268 conveyances 179 Sources of exposure 37 Rule 31. Conditions precedent to the Rule 13. Responsibilities of the licensee when the primary beam strikes 174 the wall 53. Responsibilities of the employer 55 174 Secondary barrier for scattered radiation. Emergency preparedness 180 Staff protection 237 324 . seal or Sources of radiation 9 seize radiation installation or Spatial linearity 138 radioactive material and to give Spatial resolution 141 direction to the employer 180 Specific treatment 316 Rule 32. Suspension. Inspection of premises. Power to investigate. Classified worker 173 Scattered radiation 38 Rule 19. Directives in case of accidents Spillage 112 180 Stacking test 251 Rule 33. Restriction on certain practices issuance of a license 171 172 Rule 8. Fees for license 170 condition 172 Rule 5. Decommissioning of radiation withdrawal of a license 172 installation 181 Rule 11. Records of workers 177 X-ray 42 Rule 25. Prohibition of employment of Scan localization light accuracy 135 persons below certain age 173 Scatter fraction and count rates 142 Rule 18. Responsibilities of the Service engineer 183 radiological safety officer 175 Shielding calculation 47 Rule 23. Responsibilities of worker 176 Shielding calculation for diagnostic Rule 24. Textbook of Radiological Safety Rule 10. Radiation symbol or warning Rule 9. modification or Rule 34. Exemption 170 Rule 12. Directives in the cases of Software mix-up in accelerator 303 exposures in excess of regulatory Solid waste 272 constraints 178 Somatic risk 27 Rule 29. Issuance of license 172 Rule 14. Costa Rica 303 Rule 17. 54 Rule 22. Exclusion 170 172 Rule 7. Radiation surveillance require. Modification of radiation Rule 35. Radiological safety officer 173 Sea dumping 274 Rule 2. Dose limits and other regulatory S constraints 173 Safety work practices that can reduce Rule 16. Power to appoint or recognize Source not returning to "off" position 310 persons or agencies 178 Source on position leakage 113 Rule 3. Skin and surface contamination 281 ments 178 Skin effects following exposure 313 Rule 28. Medical exposures 177 Shielding 34 Rule 27. Licence 169 Source strength verification 163 Rule 30. Rule 21. Definitions 169 Secondary barrier for leakage radiation Rule 20. Period of validity of license 172 sign 173 Rule 15. Health surveillance of workers Shielding design for computed tomo- 177 graphy 46 Rule 26. Safety standards and safety internal radiation dose 230 codes 173 San Jose. Offences and penalties 181 installation or change in working Rule 4. 146 Transport index 248 X-ray technologist 183 325 . Index Staggered autoradiography 161 Treatment control area 81 Steps to be taken in patients found to be Treatment of pregnant patients with pregnant after administration of radionuclides 235 radioiodine therapy 236 Tremcard 259 Sterility and apyrogenicity 152 Tube housing leakage 128. 109 Timer linearity 162 Work practice 206 Total filtration 126 Workers 198 Training 79 Transepidermal burn 314 X Transient erythema 313 X-ray generator 135. 137 Stochastic effect 20 Tube voltage (KVP) 124. 42. 207 Storage in transit requirements 252 Type A packages 246 Storage 274 Type B packages 247 Student/trainee 183 Type of radiation accidents 289 Survey procedure 109 Type-I (simple) 200 Swipe test 111 Type-II (medium) 201 System resolution 138 Type-III (stringent) 201 System sensitivity 140 Types of packages 246 Types of radioactive waste 270 T Types of RIA laboratories 76 Table position /increment 135 Table top exposure rate 134 U Teletherapy installation 190 Uniformity 138 Temporal accuracy 162 Use factor (U) 41 Ten day rule and its present status 29 Tenth value layer 36 W Termination of pregnancy after Warning signs and lights 86 radiation exposure 223 Waste management 267 Terrestrial radiations 9 Water immersion test 252 Test for type A package 250 Water spray test 250 Test for type B package 251 Weekly dose rate method 50 Thermal test 252 White coats and coveralls 287 Thermoluminescent dosimeter 97 Width of the primary wall 52 Thyroid shield and lead glass 205 Woman of childbearing age and nuclear Timer checking 125 medicine examinations 233 Timer error 162 Workload (W) 40. 46.