RADIATION ONCOLOGY PHYSICS: A HANDBOOK FOR TEACHERS

6,88
MB AND STUDENTS

696
stron

2348
ID International Atomic Energy Agency

2005
rok

CONTENTS

CHAPTER 1. BASIC RADIATION PHYSICS . 1

1.1. INTRODUCTION 1

1.1.1. Fundamental physical constants (rounded off to four significant figures) . 1

1.1.2. Important derived physical constants and relationships 1

1.1.3. Physical quantities and units 3

1.1.4. Classification of forces in nature . 4

1.1.5. Classification of fundamental particles 4

1.1.6. Classification of radiation . 5

1.1.7. Classification of ionizing photon radiation . 6

1.1.8. Einstein's relativistic mass, energy and momentum relationships 6

1.1.9. Radiation quantities and units . 7

1.2. ATOMIC AND NUCLEAR STRUCTURE 7

1.2.1. Basic definitions for atomic structure 7

1.2.2. Rutherford's model of the atom . 9

1.2.3. Bohr's model of the hydrogen atom 10

1.2.4. Multielectron atoms . 12

1.2.5. Nuclear structure . 14

1.2.6. Nuclear reactions 15

1.2.7. Radioactivity . 16

1.2.8. Activation of nuclides 19

1.2.9. Modes of radioactive decay 20

1.3. ELECTRON INTERACTIONS . 22

1.3.1. Electron–orbital electron interactions 23

1.3.2. Electron–nucleus interactions . 23

1.3.3. Stopping power . 24

1.3.4. Mass scattering power 25

1.4. PHOTON INTERACTIONS . 26

1.4.1. Types of indirectly ionizing photon radiation . 26

1.4.2. Photon beam attenuation 26

1.4.3. Types of photon interaction . 28

1.4.4. Photoelectric effect 28

1.4.5. Coherent (Rayleigh) scattering 29

1.4.6. Compton effect (incoherent scattering) . 30

1.4.7. Pair production . 32

1.4.8. Photonuclear reactions . 34

1.4.9. Contributions to attenuation coefficients 34

1.4.10. Relative predominance of individual effects . 36

1.4.11. Effects following photon interactions . 37

1.4.12. Summary of photon interactions . 38

1.4.13. Example of photon attenuation . 40

1.4.14. Production of vacancies in atomic shells . 41

BIBLIOGRAPHY . 43

CHAPTER 2. DOSIMETRIC PRINCIPLES, QUANTITIES AND UNITS 45

2.1. INTRODUCTION 45

2.2. PHOTON FLUENCE AND ENERGY FLUENCE 45

2.3. KERMA . 48

2.4. CEMA . 48

2.5. ABSORBED DOSE . 49

2.6. STOPPING POWER 49

2.7. RELATIONSHIPS BETWEEN VARIOUS DOSIMETRIC QUANTITIES 54

2.7.1. Energy fluence and kerma (photons) . 54

2.7.2. Fluence and dose (electrons) 56

2.7.3. Kerma and dose (charged particle equilibrium) 57

2.7.4. Collision kerma and exposure . 60

2.8. CAVITY THEORY . 61

2.8.1. Bragg–Gray cavity theory . 61

2.8.2. Spencer–Attix cavity theory . 62

2.8.3. Considerations in the application of cavity theory to ionization chamber calibration and

dosimetry protocols . 64

2.8.4. Large cavities in photon beams 66

2.8.5. Burlin cavity theory for photon beams 66

2.8.6. Stopping power ratios 68

BIBLIOGRAPHY . 70

CHAPTER 3. RADIATION DOSIMETERS . 71

3.1. INTRODUCTION 71

3.2. PROPERTIES OF DOSIMETERS 72

3.2.1. Accuracy and precision . 72

3.2.1.1. Type A standard uncertainties 72

3.2.1.2. Type B standard uncertainties 73

3.2.1.3. Combined and expanded uncertainties . 73

3.2.2. Linearity . 74

3.2.3. Dose rate dependence 74

3.2.4. Energy dependence 75

3.2.5. Directional dependence 76

3.2.6. Spatial resolution and physical size . 76

3.2.7. Readout convenience 76

3.2.8. Convenience of use 76

3.3. IONIZATION CHAMBER DOSIMETRY SYSTEMS . 77

3.3.1. Chambers and electrometers 77

3.3.2. Cylindrical (thimble type) ionization chambers 78

3.3.3. Parallel-plate (plane-parallel) ionization chambers . 79

3.3.4. Brachytherapy chambers . 79

3.3.5. Extrapolation chambers 79

3.4. FILM DOSIMETRY 81

3.4.1. Radiographic film . 81

3.4.2. Radiochromic film . 84

3.5. LUMINESCENCE DOSIMETRY 84

3.5.1. Thermoluminescence 85

3.5.2. Thermoluminescent dosimeter systems . 86

3.5.3. Optically stimulated luminescence systems 88

3.6. SEMICONDUCTOR DOSIMETRY 89

3.6.1. Silicon diode dosimetry systems . 89

3.6.2. MOSFET dosimetry systems 90

3.7. OTHER DOSIMETRY SYSTEMS 91

3.7.1. Alanine/electron paramagnetic resonance dosimetry system . 91

3.7.2. Plastic scintillator dosimetry system 92

3.7.3. Diamond dosimeters . 92

3.7.4. Gel dosimetry systems . 93

3.8. PRIMARY STANDARDS . 94

3.8.1. Primary standard for air kerma in air . 95

3.8.2. Primary standards for absorbed dose to water . 95

3.8.3. Ionometric standard for absorbed dose to water 96

3.8.4. Chemical dosimetry standard for absorbed dose to water 96

3.8.5. Calorimetric standard for absorbed dose to water 97

3.9. SUMMARY OF SOME COMMONLY USED DOSIMETRIC SYSTEMS . 97

BIBLIOGRAPHY . 99

CHAPTER 4. RADIATION MONITORING INSTRUMENTS 101

4.1. INTRODUCTION 101

4.2. OPERATIONAL QUANTITIES FOR RADIATION MONITORING . 102

4.3. AREA SURVEY METERS 103

4.3.1. Ionization chambers . 105

4.3.2. Proportional counters 105

4.3.3. Neutron area survey meters . 105

4.3.4. Geiger–Müller counters 106

4.3.5. Scintillator detectors . 107

4.3.6. Semiconductor detectors . 107

4.3.7. Commonly available features of area survey meters 108

4.3.8. Calibration of survey meters 108

4.3.9. Properties of survey meters . 110

4.3.9.1. Sensitivity 110

4.3.9.2. Energy dependence . 110

4.3.9.3. Directional dependence 111

4.3.9.4. Dose equivalent range 111

4.3.9.5. Response time . 111

4.3.9.6. Overload characteristics . 111

4.3.9.7. Long term stability . 112

4.3.9.8. Discrimination between different types of radiation 112

4.3.9.9. Uncertainties in area survey measurements . 112

4.4. INDIVIDUAL MONITORING . 113

4.4.1. Film badge . 113

4.4.2. Thermoluminescence dosimetry badge 115

4.4.3. Radiophotoluminescent glass dosimetry systems . 116

4.4.4. Optically stimulated luminescence systems 116

4.4.5. Direct reading personal monitors 117

4.4.6. Calibration of personal dosimeters . 118

4.4.7. Properties of personal monitors 118

4.4.7.1. Sensitivity 118

4.4.7.2. Energy dependence . 119

4.4.7.3. Uncertainties in personal monitoring measurements . 119

4.4.7.4. Equivalent dose range . 119

4.4.7.5. Directional dependence . 120

4.4.7.6. Discrimination between different types of radiation 120

BIBLIOGRAPHY . 120

CHAPTER 5. TREATMENT MACHINES FOR EXTERNAL BEAM RADIOTHERAPY . 123

5.1. INTRODUCTION 123