RADIATION PROTECTION AND DOSIMETRY

Transcription

1 RADIATION PROTECTION AND DOSIMETRY

2 Michael G. Stabin Radiation Protection and Dosimetry An Introduction to Health Physics 123

3 Michael G. Stabin Department of Radiology and Radiological Sciences Vanderbilt University st Avenue South Nashville, TN , personal: ISBN e-isbn Library of Congress Control Number c 2007 Springer Science+Business Media, LLC 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, 233 Springer Street, New York, NY 10013, USA), 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 in this publication of trade names, trademarks, service marks, and similar terms, even if they are not identified as such, is not to be taken as an expression of opinion as to whether or not they are subject to proprietary rights. Printed on acid-free paper springer.com

4 To the four strongest and most beautiful people that I know: Laura, Daniel, Mark, and Julia Stabin. To Dr. Charles E. Roessler, who taught me not only health physics, but the love of health physics, which I will carry with me always.

5 Table of Contents Preface xiii Acknowledgments xv Chapter 1. Introduction to Health Physics Definition of Health Physics Overview of the Role of Health Physics Employment of Health Physicists Educational Background Interaction of Health Physicists with Other Disciplines This Text and its Relation to a Training Program 4 Chapter 2. Scientific Fundamentals Quantities and Units in Science and Engineering Background Information Nature of Matter Molecules, Atoms, Quarks Excitation and Ionization Refinements to the Bohr Atom Characteristic X-rays Binding Energy The Chart of the Nuclides Some Elements of Quantum Theory Electromagnetic Radiation Wave/Particle Duality of Nature The Heisenberg Uncertainty Principle 17 Chapter 3. Radioactive Atoms Nature and Behavior Alpha Emission Positron Emission Orbital Electron Capture Beta (Minus) Emission Gamma Ray Emission Internal Conversion Electrons Auger Electrons Summary and Examples Transformation Kinetics Average Life (Mean Life) 34 vii

6 viii Table of Contents 3.11 Specific Activity Series Decay Time of Maximum Progeny Activity Tracing Radioactive Decay on the Chart of the Nuclides 40 Chapter 4. Interaction of Radiation with Matter Charged Particle Interaction Mechanisms Alpha Particle Interactions Beta Particle Interactions Specific Ionization Mass Stopping Power Linear Energy Transfer (LET) Bremsstrahlung Radiation Gamma Ray Interactions Mechanisms Photoelectric Effect Compton Effect Pair Production Photodisintegration Photon Attenuation and Absorption Coefficients Neutron Interactions Scattering Absorption 64 Chapter 5. Quantities and Units in Radiation Protection Exposure Absorbed Dose and Equivalent Dose Radioactivity Particle and Energy Field Units 74 Chapter 6. Biological Effects of Radiation Introduction: Background Mechanisms of Radiation Damage to Biological Systems Biological Effects in Humans Nonstochastic Effects Death from Whole Body Exposure The Acute Radiation Syndrome Hemopoetic Syndrome Gastrointestinal (GI) Syndrome Central Nervous System (CNS) Syndrome Damage to Skin Gonads Cataract Formation Stochastic Effects Cancer Leukemia Bone Cancer Lung Cancer Thyroid Cancer 97

7 Table of Contents ix Hereditary Effects Mathematical Models of Cancer Risk Cell Survival Studies Relative Biological Effectiveness 102 Chapter 7. The Basis for Regulation of Radiation Exposure Period 1: Period 2: Period 3: Period 4: Period 5: Period 6: Period 7: Period 8: Period 9: Period 10: 1966 Present Period 11: The Future Radiation Regulations An Acronym-onious History Introduction Scientific Advisory Bodies Regulatory Bodies 119 Chapter 8. Health Physics Instrumentation Thermal Reactions Chemical Reactions Electrical Devices Gas Filled Detectors Light Production: Scintillation Detectors Semiconductor Detectors Alpha and Gamma Spectroscopy/Spectrometry Personnel Monitoring Neutron Detection Calibration Considerations Photons Electrons/Beta Alpha Neutrons Counting Statistics Gaussian Distribution Poisson Distribution Propagation of Errors Mean Value of Multiple Independent Counts Minimum Detectable Activity Optimization of Limited Counting Time 176 Chapter 9. External Dose Assessment Dose from Discrete Photon Sources Specific Gamma Ray Emission Factor Point Source Line Source 182

8 x Table of Contents Plane Source Volume Source Dose from Discrete Electron Sources Hot Particles Dose from Discrete Neutron Sources Dose from Extended Sources Tritium and Noble Gases Computer Modeling in External Dose Assessment Literature Resources in External Dose Assessment 202 Chapter 10. Internal Dose Assessment Basic Concepts in Internal Dose Calculations Effective Half-Time Dosimetry Systems Marinelli Quimby Method International Commission on Radiological Protection Medical Internal Radiation Dose (MIRD) System RADAR Internal Dose Calculations for Radiation Workers Internal Dose Calculations for Nuclear Medicine Patients 228 Chapter 11. Radiation Protection Practice/Evaluation Introduction External Protection Principles Shielding of Photon Sources Graded or Laminated Shielding Shielding of X-Ray Sources Shielding of Discrete Electron Sources Shielding of Neutron Sources Performing Radiation Surveys Principles of Optimization Protection of Workers from Internal Contamination Air Sampling Calculations Methods for Gathering Bioassay Data In-Vivo Counting In-vitro Measurements Interpretation of Bioassay Data Criticality and Criticality Control 291 Chapter 12. Environmental Monitoring for Radiation Types of Environmental Assessment Programs Types of Facilities Monitored Types of Samples and Sampling Strategies Direct Gamma Exposure Readings Airborne Concentrations of Radionuclides Long-Term Off-Site Monitoring Concentrations of Radionuclides in Water Concentrations of Radionuclides in Soil or Sediment Concentrations of Radionuclides in Biological Species (Biota) General Sampling Strategies and Techniques 323

9 Table of Contents xi 12.6 Sample Management Instrumentation Evaluation of the Data Radioactive Waste Management The Nuclear Fuel Cycle General Waste Types Site Evaluation 343 Chapter 13. Nonionizing Radiation Ultraviolet Radiation Lasers Radiofrequency Radiation, and Microwave Sources EMF Magnetic Resonance Imaging (MRI) 368 Index 373

10 Preface This text is meant to serve as the basis for a two-course series in the study of radiation protection (a.k.a. health physics ). The first course would be an introduction to and fast-paced overview of the subject. For some, this is the only course in radiation protection that they will take, and thus all material must be covered in a fairly superficial and rapid fashion. The second course is a more in-depth and applied study of radiation protection, bringing in current materials from the literature, a detailed study of regulations, practice with realworld dose and shielding calculations, and perhaps application in a semesterlong student project assigned by the instructor. Several chapters include an additional section of suggested readings and other resources that can be used by the instructor to build such detailed investigations in a second course of this nature. In the first course, the chapter may be basically studied, with reference to the idea that a much richer literature base exists than can be covered in a broad overview of radiation protection. Through exploration of this literature base, and other similar materials that the instructor may be aware of that are not specifically cited, this second, more in-depth course may be developed. A routine part of any good health physics program is a complete course in radiation detection and measurement. My brief overview chapter here cannot provide the depth needed for this subject. Most instructors are familiar with the excellent book by Glenn Knoll on the subject, which I heartily recommend as the basis for such a full course. Most chapters have some exercises for the student. I have provided the problem and the answer and worked-out solution in all cases. It is not advisable that the students be provided with the worked-out solutions, as this will certainly encourage laziness of approach with some students. These are for the instructor s use; students should be given the problems and correct answers, to guide their work, and then shown individual solutions as needed to clarify difficult areas. All of the problem questions and solutions are available from the RADAR web site ( it is hoped that they will be of value to the instructor. Any errors found in the textbook or problem solutions should naturally be forwarded to the author. xiii

11 Acknowledgments I note the input and inspiration of other professors and teachers whose excellence gave me models to follow in my work and teaching. There are, of course, many to whom credit is due. Besides Dr. Charles E. Roessler, to whom the book is dedicated, I single out for notable mention, Dr. Roger A. Gater and Dr. Genevieve S. Roessler of the University of Florida and Dr. Paul W. Frame of the Oak Ridge Institute for Science and Education. Special thanks to Ms. Mary Ann Emmons, who convinced me to organize my many scattered thoughts about health physics in this volume and make them available to others. xv