Physics and Radio biology of Nuclear Medicine

Gopal B. Saha

Physics and Radiobiology of Nuclear Medicine

With 76 Illustrations

Springer Science+Business Media, LLC

Gopal B. Saha, Ph.D. Department of Nuclear Medicine The Cleveland Clinic Foundation Cleveland, OH 44195 USA

Library of Congress Cataloging-in-Publication Data Saha, Gopal B.

Physics and Radiobiology of Nuclear Medicine / Gopal B. Saha. p. cm.

Includes bibliographical references and index. ISBN 978-1-4757-6186-3 ISBN 978-1-4757-6184-9 (eBook) DOI 10.1007/978-1-4757-6184-9 1. Medical Physics. 2. Nuclear medicine. 3. Radiobiology. I. Title. [DNLM. 1. Nuclear Medicine. 2. Biophysics. 3. Radiobiology. WN

440 Sl31p] R895.S25 1993 616.07'575-dc20 DNLM/DLC for Library of Congress

Printed on acid-free paper.

© 1993 Springer Science+Business Media New York Originally published by Springer-Verlag New York, Inc. in 1993

93-635

All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher (Springer Science+Business Media, LLC), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use of general descriptive names, trade names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. While the advice and information in this book are believed to be true and accurate at the date of going to press, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.

Production managed by Hal Henglein, manufacturing supervised by Vincent R. Scelta. Typeset by Asco Trade Typesetting Ltd., Hong Kong.

9 8 7 6 543 2 1

ISBN 978-1-4757-6186-3

To: My mother, Charubala, My father, the late Hriday Ranjan, My wife, Sipra and My children, Prantik and Trina

Preface

A basic knowledge of physics, instrumentation, and radiobiology is essential for nuclear physicians and technologists in the practice of nuclear medicine. The nuclear medicine specialty has matured over the past three decades to the extent that there is an increasing need for certification of physicians and technologists to practice nuclear medicine. Each year many medical residents take the American Board of Nuclear Medicine examination and the Ameri­can Board of Radiology examination with special competency in Nuclear Radiology, and many technologists take the Registry examination in Nuclear Medicine. All these tests include a good portion of physics, instrumenta­tion, and radiobiology in nuclear medicine. It is mandatory that radiology residents pass the physics section of the American Board of Radiology examination.

This book is primarily addressed to this audience. In addition, anyone in­terested in the basics of physics, instrumentation, and radiobiology in nuclear medicine should find this book useful.

The book contains 14 chapters. Chapters 1 to 6 deal with the basic proper­ties of the atom and nucleus, radionuclidic decay, statistics of counting, pro­duction of radionuclides, and interaction of radiation with matter. In Chap­ters 7 to 11, various instruments such as ionization chambers, gamma well counters, thyroid probes, gamma cameras, and tomographic scanners (single photon emission computed tomography and positron emission tomography) are described. The principles of operation and various parameters affecting the operation of these instruments are included in these chapters. Chapter 12 presents a brief account of radiobiology, highlighting the effects of radia­tion on humans. Chapter 13 describes the calculation of internal dosimetry. Various regulations related to radiation protection are presented in Chapter 14. Included at the end of the book are several appendices on various con­stants, a glossary of terms used in the text, and answers to mathematical problems given at the end of each chapter.

The book is concise but comprehensive, with an emphasis on the basic principles of each topic. Sufficient illustrations have been included to help the reader understand the appropriate subject matter. At the end of each chapter,

vii

VIII Preface

questions related to the specific topic are provided to provoke the reader to assess the sufficiency of knowledge gained. These questions should be very helpful for those taking the certification examinations.

I do not pretend to be infallible in writing a book of such diversified scientific information. Many errors of both commission and omission may have occurred, and I would appreciate having them brought to my attention by interested readers.

Several individuals were very helpful to me during this project. First and foremost, I am ever grateful to Dr. W.1. MacIntyre of our department, whose perusal of the manuscript and numerous suggestions and ideas were abso­lutely essential for this book. I thank Dr. M.K. Dewanjee of the University of Miami School of Medicine, Miami, Florida, for many helpful suggestions. Thanks are due to Mr. Bruno Sufka of our department, for clarifying some of the issues related to the computer application. Assistance from all members of our department is greatly appreciated.

I am grateful to Dr. R.T. Go, Chairman of our department, whose con­tinued support and understanding have made my work enjoyable.

I express my heartfelt thanks and appreciation to Ms. Rita Buzzelli for typing the manuscript many times over, graciously, conscientiously, and effi­ciently, and for her dedicated effort which played a monumental role in bringing this book to fruition.

I thank the publisher, Springer-Verlag, for their sincere cooperation throughout the project.

Finally, my wife Sipra's forbearance and encouragement during this en­deavor made work a pleasure.

Gopal B. Saha

Contents

Preface .................................................... vii

Chapter 1 Structure of Matter ................................ 1 Matter and Energy ........................................ 1

Radiation .............................................. 1 The Atom ................................................ 3

Electronic Structure of the Atom ........................... 3 Structure of the Nucleus .................................. 6

Nuclear Nomenclature ..................................... 8 Chart of the Nuclides ...................................... 8 Questions ................................................ 10 Suggested Readings ........................................ 10

Chapter 2 Radioactive Decay ................................ 11 Isomeric Transition ........................................ 11 Alpha (oc) Decay ........................................... 14 Beta (13-) Decay ........................................... 14 Positron (p+) Decay ....................................... 17 Electron Capture .......................................... 18 Questions ................................................ 19 Suggested Readings ........................................ 20

Chapter 3 Kinetics of Radioactive Decay ....................... 21 Radioactive Decay Equations ............................... 21

General Equation ....................................... 21 Half-Life ............................................... 23 Mean Life .............................................. 25 Effective Half-Life ....................................... 25

Units of Radioactivity ...................................... 26 Specific Activity ........................................... 26 Calculation ............................................... 27 Successive Decay Equations ................................. 29

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x Contents

General Equation ....................................... 29 Transient Equilibrium .................................... 30 Secular Equilibrium ...................................... 31

Questions ................................................ 32 Suggested Readings ........................................ 33

Chapter 4 Statistics of Radiation Counting ..................... 34 Error, Accuracy, and Precision .............................. 34 Mean and Standard Deviation ............................... 34 Standard Deviation of Count Rates .......................... 36 Propagation of Errors ...................................... 37 Questions ................................................ 39 Sugge~edReadings ........................... .... ......... 39

Chapter 5 Production of Radionuclides ........................ 40 Cyclotron-Produced Radionuclides ........................... 40 Reactor-Produced Radionuclides ............................ 42

Fission or (n,f) Reaction ................................. 43 Neutron Capture or (n, y) Reaction ......................... 43

Target and Its Processing ................................... 45 Equation for Production of Radionuclides ..................... 45 Radionuclide Generators ................................... 47

99Mo_99mTc Generator .................................. 48 Questions ................................................ 49 Suggested Readings ........................................ 50

Chapter 6 Interaction of Radiation With Matter ................ 51 Interaction of Charged Particles With Matter .................. 51

Specific Ionization ....................................... 52 Linear Energy Transfer ................................... 52 Range ................................................. 53 Bremsstrahlung ......................................... 54 Annihilation ............................................ 55

Interaction of y-Radiations With Matter ...................... 55 Mechanism of Interaction of y-Radiations ................... 55 Attenuation of y-Radiations ............................... 58

Interaction of Neutrons With Matter ......................... 62 Questions ................................................ 62 Suggested Readings ........................................ 64

Chapter 7 Gas-Filled Detectors ............................... 65 Principles of Gas-Filled Detectors ............................ 65 Ionization Chambers ....................................... 68

Cutie Pie Survey Meter ................................... 68 Dose Calibrator ......................................... 68

Contents xi

Pocket Dosimeter ....................................... 70 Geiger-Muller Counters ................................... 70 Questions ................................................ 72 Suggested Readings. . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . 72

Chapter 8 Scintillation and Semiconductor Counters ............ 73 Principles of Scintillation Detectors .......................... 73 Solid Scintillation Counters ................................. 73

NaI(TI) Detector ........................................ 74 Photomultiplier Tube .................................... 75 Preamplifier ............................................ 75 Linear Amplifier ........................................ 75 Pulse-Height Analyzer ................................... 76 Display or Storage ...................................... 76

Gamma-Ray Spectrometry ................................. 76 Photopeak ............................................. 77 Compton Valley, Edge, and Plateau ........................ 78 Characteristic X-ray Peak ................................ 79 Backscatter Peak ........................................ 79 Iodine Escape Peak ...................................... 79 Annihilation Peak ....................................... 80 Coincidence Peak ....................................... 80

Liquid Scintillation Counters ............................... 81 Semiconductor Detectors ................................... 83 Cadmium-Telluride Detectors ............................... 83 Characteristics of Counting Systems .......................... 84

Energy Resolution ....................................... 84 Detection Efficiency ..................................... 85 Dead Time ............................................. 87

Gamma Well Counters... . ..... ... ..... ....... . . . ....... ... 88 Thyroid Probe ............................................ 91 Questions ................................................ 92 Suggested Readings ........................................ 94

Chapter 9 Imaging Devices .................................. 95 Rectilinear Scanners ....................................... 95 Scintillation or Gamma Cameras ............................ 97

Principles of Operation .................................. 98 Detector ............................................... 99 Collimator ............................................. 100 Photomultiplier Tube .................................... 101 X-, Y-Positioning Circuit ................................. 101 Pulse-Height Analyzer ................................... 103 Display and Recording Systems ........................... 103 Digital Computer ....................................... 104

xii Contents

M ulticrystal Cameras ...................................... 105 Questions ................................................ 105 References and Suggested Readings ........................... 106

Chapter 10 Performance Parameters oflmaging Devices ......... 107 Spatial Resolution ......................................... 107

Gamma Camera ..................................... , . .. 107 Rectilinear Scanner ...................................... 111 Blur ................................................... 111 Evaluation of Spatial Resolution ........................... 111

Sensitivity ................................................ 116 Collimator Efficiency ..................................... 116

Uniformity ............................................... 117 Contrast ................................................. 119 Quality Control Tests for Gamma Cameras. . . . . . . . . . . . . . . . . . .. 120

Daily Checks ........................................... 120 Weekly Checks .......................................... 121

Questions ................................................ 121 References and Suggested Readings ........................... 123

Chapter 11 Tomographic Imaging Devices ..................... 124 General Considerations ..................................... 124 Single Photon Emission Computed Tomography ............... 125

Image Reconstruction .................................... 125 Factors Affecting SPECT ................................. 129

Positron Emission Tomography ............................. 131 Factors Affecting PET .................................... 132

Quality Control Tests for SPECT and PET .................... 135 Questions ................................................ 136 References and Suggested Readings ........................... 137

Chapter 12 Radiation Biology ................................ 138 The Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 138 Radiation Units ........................................... 140 Effects of Radiation on Cells ................................ 142 Direct and Indirect Action of Radiation ....................... 143 Radiosensitivity of Cells .................................... 143 Cell Survival Curves ....................................... 144 Factors Affecting Cell Response to Radiation .................. 146

Dose Rate .............................................. 146 Linear Energy Transfer ................................... 147 Chemicals .............................................. 147 Stage of Cell Cycle ....................................... 149

Short-Term Effects of Total Body Irradiation .................. 149

Contents xiii

Hemopoietic Death ...................................... 150 Gastrointestinal Death ................................... 150 Central Nervous System Death ............................ 150

Long-Term Effects of Radiation. . . . . . . . . . . . . . . . . . . . . . . . . . .. .. 150 Somatic Effects .......................................... 151 Genetic Effects .......................................... 154

Questions ................................................ 156 References and Suggested Readings ........................... 157

Chapter 13 Internal Radiation Dosimetry ...................... 158 Dose Calculation .......................................... 158

Radiation Dose Rate ..................................... 158 Cumulative Radiation Dose ............................... 160 Radiation Dose in SI Units ............................... 161

Pediatric Dosages ......................................... 162 Questions ................................................ 165 References and Suggested Readings ........................... 166

Chapter 14 Radiation Protection and Regulations ............... 167 Radiation Protection ....................................... 167

Definition of Terms ...................................... 167 Sources of Radiation Exposure ............................ 169 Radiation Dose Limits ................................... 170 Principles of Radiation Protection ......................... 171 Personnel Monitoring .................................... 173 Dos and Don'ts in Radiation Protection Practice ............. 175

Radiation Regulations ...................................... 175 Nuclear Regulatory Commission ........................... 175 License ................................................ 175 Radiation Safety Committee ............................... 176 Radiation Safety Officer .................................. 176 ALARA Program ........................................ 176 Medical Uses of Radioactive Materials ...................... 177 Survey for Contamination and Exposure Rate ................ 177 Dose Calibrators and Survey Meters ....................... 177 Caution Signs and Labels ................................. 178 Bioassay ............................................... 179 Receiving and Monitoring of Radioactive Packages ........... 179 Radioactive Waste Disposal ............................... 180 Radioactive Spill ........................................ 181 Record Keeping ......................................... 182 Transportation of Radioactive Materials .................... 182

Questions ................................................ 183 References and Suggested Readings ........................... 184

xiv Contents

Appendix A Units and Constants ............................. 186 Appendix B Terms Used in Text .............................. 188 Appendix C Answers to Questions ............................ 193

Index ...................................................... 197