Physics and Radiobiology of Nuclear Medicine (eBook)

Preface 6
Table of Contents 8
1 Structure of Matter 16
Matter and Energy 16
Radiation 16
The Atom 18
Electronic Structure of the Atom 18
Structure of the Nucleus 21
Nuclear Binding Energy 22
Nuclear Nomenclature 23
Chart of the Nuclides 23
Questions 25
Suggested Readings 25
2 Radioactive Decay 26
Spontaneous Fission 26
Isomeric Transition 27
Gamma (.)-Ray Emission 27
Internal Conversion 28
Alpha (a)-Decay 29
Beta (ß )-Decay 30
Positron (ß+)-Decay 32
Electron Capture 34
Questions 35
Suggested Readings 35
3 Kinetics of Radioactive Decay 36
Radioactive Decay Equations 36
General Equation 36
Half-Life 37
Mean Life 40
Effective Half-Life 40
Units of Radioactivity 41
Specific Activity 41
Calculation 42
Successive Decay Equations 44
General Equation 44
Transient Equilibrium 45
Secular Equilibrium 47
Questions 47
Suggested Readings 48
4 Statistics of Radiation Counting 49
Error, Accuracy, and Precision 49
Mean and Standard Deviation 50
Gaussian Distribution 50
Standard Deviation of Count Rates 52
Propagation of Errors 52
Chi-Square Test 54
Minimum Detectable Activity 56
Evaluation of Diagnostic Tests 56
Questions 58
Suggested Readings 58
5 Production of Radionuclides 59
Cyclotron-Produced Radionuclides 59
Reactor-Produced Radionuclides 61
Fission or (n, f) Reaction 62
Neutron Capture or (n, . ) Reaction 62
Target and Its Processing 64
Equation for Production of Radionuclides 64
Radionuclide Generators 66
Questions 69
Suggested Readings 70
6 Interaction of Radiation with Matter 71
Interaction of Charged Particles with Matter 71
Specific Ionization 72
Linear Energy Transfer 72
Range 73
Bremsstrahlung 75
Annihilation 75
Interaction of . -Radiations with Matter 75
Mechanism of Interaction of . -Radiations 75
Photoelectric Effect 76
Compton Scattering 77
Pair Production 78
Photodisintegration 79
Attenuation of .-Radiations 79
Linear and Mass Attenuation Coefficients 79
Interaction of Neutrons with Matter 83
Questions 83
Suggested Readings 85
7 Gas-Filled Detectors 86
Principles of Gas-Filled Detectors 86
Ionization Chambers 89
Cutie Pie Survey Meter 89
Dose Calibrator 89
Constancy 91
Accuracy 91
Linearity 91
Geometry 92
Pocket Dosimeter 92
Geiger–Müller Counters 92
Questions 94
Suggested Readings 95
8 Scintillation and SemiconductorDetectors 96
Scintillation Detectors 96
Solid Scintillation Detectors 97
NaI (Tl) Detector 97
Bismuth Germanate Detector 97
Barium Fluoride Detector 97
Lutetium Oxyorthosilicate Detector 99
Gadolinium Oxyorthosilicate Detector 99
Yttrium Oxyorthosilicate Detector 99
Semiconductor Detectors 99
Germanium and Silicon Detectors 99
Cadmium–Zinc–Tellurium Detector 100
Cesium Iodide (CsI(Tl)) Detector 100
Solid Scintillation Counters 101
NaI(Tl) Detector 101
Photomultiplier Tube 101
Preamplifier 102
Linear Amplifier 102
Pulse-Height Analyzer 102
Display or Storage 103
Gamma-Ray Spectrometry 103
Photopeak 104
Compton Valley, Edge, and Plateau 104
Characteristic X-Ray Peak 105
Backscatter Peak 106
Iodine Escape Peak 106
Annihilation Peak 107
Coincidence Peak 107
Liquid Scintillation Counters 108
Characteristics of Counting Systems 110
Energy Resolution 110
Detection Efficiency 111
Intrinsic Efficiency 112
Photopeak Efficiency or Photofraction 112
Geometric Efficiency 112
Dead Time 114
Gamma Well Counters 116
Calibration of Well Counters 116
Counting in Well Counters 117
Effects of Sample Volume 118
Thyroid Probe 119
Thyroid Uptake Measurement 120
Questions 120
Suggested Readings 122
9 Gamma Cameras 123
Gamma Cameras 123
Principles of Operation 123
Detector 125
Collimator 126
Photomultiplier Tube 127
X-, Y-Positioning Circuit 127
Pulse-Height Analyzer 129
Display and Storage 129
Digital Cameras 130
Solid-State Digital Cameras 131
Questions 131
Suggested Readings 132
10 Performance Parameters of Gamma Cameras 133
Spatial Resolution 133
Intrinsic Resolution 133
Collimator Resolution 134
Scatter Resolution 136
Evaluation of Spatial Resolution 137
Bar Phantom 137
Line-Spread Function 139
Modulation Transfer Function 140
Sensitivity 142
Collimator Efficiency 143
Uniformity 144
Pulse-Height Variation 144
Nonlinearity 145
Edge Packing 146
Gamma Camera Tuning 146
Effects of High Counting Rates 147
Contrast 147
Quality Control Tests for Gamma Cameras 148
Daily Checks 149
Weekly Checks 151
Annual or As-Needed Checks 151
Questions 151
References and Suggested Readings 153
11 Digital Computers in Nuclear Medicine 154
Basics of a Computer 154
Central Processing Unit 155
Computer Memory 156
External Storage Devices 156
Input/Output Devices 156
Operation of a Computer 157
Digitization of Analog Data 157
Digital-to-Analog Conversion 158
Digital Images 158
Application of Computers in Nuclear Medicine 159
Digital Data Acquisition 159
Static Study 161
Dynamic Study 161
Gated Study 162
Reconstruction of Images 162
Superimposition and Subtraction of Images 162
Display 163
Software and DICOM 164
PACS 165
Questions 167
Suggested Readings 167
12 Single Photon Emission Computed Tomography 168
Tomographic Imaging 168
Single Photon Emission Computed Tomography 168
Data Acquisition 170
Image Reconstruction 171
Simple Backprojection 171
Iterative Reconstruction 181
SPECT/CT 184
Factors Affecting SPECT 186
Photon Attenuation 186
Center of Rotation 190
Sampling 191
Scattering 191
Performance of SPECT Cameras 192
Spatial Resolution 192
Sensitivity 192
Other Parameters 192
Quality Control Tests for SPECT Cameras 193
Daily Tests 193
Photopeaking and Uniformity 193
Weekly Tests 193
Spatial Resolution 193
Center of Rotation 193
Quality Control Tests for CT Scanners 194
Questions 195
References and Suggested Readings 195
13 Positron Emission Tomography 197
Positron-Emitting Radionuclides 197
Detector for PET 198
PM Tubes and Pulse-Height Analyzers 198
PET Scanners 199
Block Detectors 199
Coincidence Timing Window 199
PET/CT Scanners 204
Mobile PET or PET/CT 205
Micro-PET 205
Hybrid Gamma Cameras 206
Data Acquisition 206
Two-Dimensional Versus Three-Dimensional Data Acquisition 209
Image Reconstruction 211
Factors Affecting PET 211
Normalization 211
Photon Attenuation Correction 212
Random Coincidences 214
Scatter Coincidences 215
Dead Time 215
Radial Elongation 215
Performance of PET Scanners 216
Spatial Resolution 216
Sensitivity 219
Noise Equivalent Count Rate 219
Quality Control Tests for PET Scanners 220
Daily Tests 220
Sinogram Check 220
Weekly Tests 220
Normalization 220
Questions 221
References and Suggested Readings 221
14 Internal Radiation Dosimetry 223
Radiation Units 223
Dose Calculation 226
Radiation Dose Rate 226
Cumulative Radiation Dose 227
Radiation Dose in SI Units 231
Effective Dose Equivalent and Effective Dose 235
Pediatric Dosages 237
Questions 238
References and Suggested Readings 239
15 Radiation Biology 241
The Cell 241
Effects of Radiation 245
DNA Molecule 245
Chromosome 246
Direct and Indirect Actions of Radiation 250
Radiosensitivity of Cells 252
Cell Survival Curves 253
Factors Affecting Radiosensitivity 256
Dose Rate 256
Linear Energy Transfer 257
Chemicals 257
Radiosensitizers 257
Radioprotectors 259
Stage of Cell Cycle 260
Classification of Radiation Damage 260
Stochastic and Deterministic Effects 261
Acute Effects of Total Body Irradiation 262
Hemopoietic Syndrome 262
Gastrointestinal Syndrome 263
Cerebrovascular Syndrome 263
Long-Term Effects of Radiation 264
Somatic Effects 264
Carcinogenesis 264
Epidemiologic Evidence of Carcinogenesis 265
Dose–Response Relationship 266
Risk Estimates of Excess Cancer 267
Leukemia 267
Breast Cancer 268
Other Cancers 268
Radiation Damage to Skin 268
Radiation Damage to Reproductive Organs 269
Nonspecific Life-Shortening 269
Cataractogenesis 270
Radiation Damage to Embryo and Fetus 270
Genetic Effects 271
Spontaneous Mutations 271
Doubling Dose 271
Genetically Significant Dose 272
Risk Versus Benefit in Diagnostic Radiology and Nuclear Medicine 273
Risk to Pregnant Women 274
Dirty Bombs 275
Types of Radiation Exposure 276
Protective Measures in Case of Explosion of a Dirty Bomb 277
Verification Card for Radioactive Patients 277
Radiation Phobia 278
Questions 280
References and Suggested Readings 282
16 Radiation Regulations and Protection 283
Sources of Radiation Exposure 283
License 285
Radiation Protection 286
Definition of Terms 286
Caution Signs and Labels 287
Occupational Dose Limits 288
ALARA Program 289
Principles of Radiation Protection 289
Time 289
Distance 290
Shielding 291
Activity 292
Personnel Monitoring 292
Film Badge 292
Thermoluminescent Dosimeter 293
Dos and Don’ts in Radiation Protection Practice 294
Bioassay 294
Receiving and Monitoring of Radioactive Packages 295
Radioactive Waste Disposal 295
Decay in Storage 296
Release into Sewerage System 296
Transfer to Authorized Recipient 296
Other Disposal Methods 297
Radioactive Spill 297
Recordkeeping 297
Medical Uses of Radioactive Materials 298
Applications, Amendments, and Notifications 298
Authority and Responsibilities of the Licensee 299
Supervision 299
Mobile Nuclear Medicine Service 300
Written Directives 300
Measurement of Dosages 300
Calibration, Transmission, and Reference Sources 301
Requirement for Possession of Sealed Sources 301
Labeling of Vials and Syringes 301
Surveys of Ambient Radiation Exposure Rate 302
Calibration of Survey Instruments 302
Training and Experience Requirements for Medical Uses of By-Product Materials 302
Report and Notification of a Medical Event 303
Report and Notification of a Dose to an Embryo/Fetus or a Nursing Child 304
Release of Patients Administered with Radiopharmaceuticals 305
Recordkeeping 306
Transportation of Radioactive Materials 308
European Regulations Governing Radiopharmaceuticals 310
Questions 312
References and Suggested Readings 313
Appendix A Units and Constants 315
Appendix B Terms Used in Text 317
Appendix C Answers to Questions 322
Index 323

"6 Interaction of Radiation with Matter (p. 56)

All particulate and electromagnetic radiations can interact with the atoms of an absorber during their passage through it, producing ionization and excitation of the absorber atoms. These radiations are called ionizing radiations. Because particulate radiations have mass and electromagnetic radiations do not, the latter travel through matter longer distance before losing all energy than the former of the same energy. Electromagnetic radiations are therefore called penetrating radiations and particulate radiations nonpenetrating radiations.The mechanisms of interaction with matter, however, differ for the two types of radiation, and therefore they are discussed separately.

Interaction of Charged Particles with Matter

The energetic charged particles such as a-particles, protons, deuterons, and b-particles (electrons) interact with the absorber atoms, while passing through it.The interaction occurs primarily with the orbital electrons of the atoms and rarely with the nucleus. During the interaction, both ionization and excitation as well as the breakdown of the molecule may occur. In excitation, the charged particle transfers all or part of its energy to the orbital electrons, raising them to higher energy shells. In ionization, the energy transfer may be suf?cient to overcome the binding energy of the orbital electrons, ultimately ejecting them from the atom.

Electrons ejected from the atoms by the incident charged particles are called primary electrons, which may have suf?cient kinetic energy to produce further excitation or ionization in the absorber. The high-energy secondary electrons from secondary ionizations are referred to as delta (d-) rays. The process of excitation and ionization will continue until the incident particle and all electrons come to rest. Both these processes may rupture chemical bonds in the molecules of the absorber, forming various chemical entities. In ionization, an average energy of W is required to produce an ion pair in the absorber and varies somewhat with the type of absorber.

The value of W is about 35 eV in air and less in oxygen and xenon gases but falls in the range of 25–45 eV for most gases. The process of ionization, that is, the formation of ion pairs, is often used as a means of the detection of charged particles in ion chambers and Geiger–Müller counters described in Chapter 7. Three important quantities associated with the passage of charged particles through matter are speci?c ionization, linear energy transfer, and range of the particle in the absorber, and these are described next."