The Essential Physics of Medical Imaging Study Guide

Dedication iii
Authors iv
Contributors vi
Acknowledgments vii
Section I: Basic Concepts ....................................................... 1
1 Introduction to the Study Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1 .0 Introduction 3
1 .1 Section I: Chapter Summary 3
1 .2 Section II: Questions and Explanatory Answers 5
1 .3 Section III: Key Equations, Symbols, Quantities, and Units 5
1 .4 Study Smarter, Not Harder 6
1 .5 Preparing for and Taking Major Exams 8
2 Radiation and the Atom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2 .0 Introduction 10
2 .1 Classical Electromagnetism 10
2 .2 Electromagnetic Radiation 11
2 .3 Behavior of Energy at the Atomic Scale: One of the Most Important
Discoveries in the History of Science 13
2 .4 Ionizing and Nonionizing Radiation 13
2 .5 Particulate Radiation 14
2 .6 Mass-Energy Equivalence 14
2 .7 Structure of the Atom 14
2 .8 Radiation from Electron Transitions 16
2 .9 The Atomic Nucleus 16
2 .10 Nuclear Stability and Radioactivity 17
2 .11 Nuclear Binding Energy and Mass 19
Section II Questions and Answers 21
Section III Key Equations and Symbols 25
3 Interaction of Radiation with Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3 .0 Introduction 26
3 .1 Particle Interactions 26
3 .2 X-Ray and Gamma-Ray Interactions 28
3 .3 Attenuation of X-Rays and Gamma Rays 31
3 .4 Absorption of Energy from X-Rays and Gamma Rays 33
3 .5 Imparted Energy, Equivalent Dose, and Effective Dose 34
Section II Questions and Answers 36
Section III Key Equations and Symbols 40
4 Image Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4 .0 Introduction 42
4 .1 Spatial Resolution 42
4 .2 Contrast Resolution 45
4 .3 Noise and Noise Texture 46
4 .4 Ratio Measures of Image Quality 47
4 .5 Image Quality Measures Based on Visual Performance 48
Section II Questions and Answers 51
Section III Key Equations and Symbols 56
5 Medical Imaging Informatics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5 .0 Introduction 58
5 .1 Ontologies, Standards, Profiles 58
5 .2 Computers and Networking 59
5 .3 Picture Archiving and Communications System 63
5 .4 Life Cycle of a Radiology Examination 69
5 .5 Radiology from Outside the Department 71
5 .6 Security and Privacy 72
5 .7 “Big Data” and Data Plumbing 74
5 .8 Algorithms for Image and Nonimage Analytics 74
5 .9 The Business of Informatics 77
5 .10 Beyond Imaging Informatics 77
ContentsSection II Questions and Answers 78
Section III Key Equations and Symbols 83
SECTION II: Diagnostic Radiology ............................................... 85
6 X-Ray Production, Tubes, and Generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
6 .0 Introduction 87
6 .1 Production of X-Rays 87
6 .2 X-Ray Tubes 89
6 .3 X-Ray Generators 93
6 .4 Power Ratings, Anode Loading and Cooling 95
6 .5 Factors Affecting X-Ray Emission 96
Section II Questions and Answers 98
Section III Key Equations and Symbols 102
7 Radiography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
7 .0 Introduction 103
7 .1 Geometry of X-Ray Projection 103
7 .2 Scattered Radiation in Projection Radiographic Imaging 104
7 .3 Technique Factors in Radiography 107
7 .4 Scintillators and Intensifying Screens 108
7 .5 Absorption Efficiency and Conversion Efficiency 108
7 .6 Computed Radiography 109
7 .7 Charge-Coupled Device and Complementary Metal-Oxide Semiconductor Devices 110
7 .8 Flat Panel Thin-Film Transistor Array Detectors 111
7 .9 Other Considerations 113
7 .10 Radiographic Detectors, Patient Dose, and Exposure Index 113
7 .11 Artifacts in Digital Radiography 115
7 .12 Special Considerations for Pediatric Digital Radiography 117
7 .13 Dual-Energy Subtraction Radiography 117
Section II Questions and Answers 119
Section III Key Equations and Symbols 125
8 Breast Imaging: Mammography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
8 .0 Introduction 127
8 .1 X-Ray Tube Components, Structures, and Operation 127
8 .2 X-Ray Generator 131
8 .3 Compression, Scattered Radiation, and Magnification 132
8 .4 Digital Acquisition Systems 134
8 .5 Processing, Viewing, Analyzing Breast Mammogram Images 138
8 .6 Radiation Dosimetry 140
8 .7 Regulatory Requirements 142
Section II Questions and Answers 145
Section III Key Equations and Symbols 151
9 Fluoroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
9 .0 Introduction 152
9 .1 Fluoroscopic Imaging Chain Overview 152
9 .2 Imaging Chain Components 153
9 .3 Fluoroscopic X-Ray Source Assembly 155
9 .4 Controls 156
9 .5 Modes of Operation 157
9 .6 Image Processing 159
9 .7 Image Quality in Fluoroscopy 161
9 .8 Patient Radiation Management 163
9 .9 Operator and Staff Radiation Safety 165
9 .10 Looking Ahead 165
Section II Questions and Answers 167
Section III Key Equations and Symbols 173
10 Computed Tomography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
10 .0 Introduction 174
10 .1 Basic Concepts 175
10 .2 CT System Designs 176
10 .3 Acquisition Modes 182
10 .4 Reconstruction 187
10 .5 Image Quality in CT 192
10 .6 CT Image Artifacts 194
Section II Questions and Answers 198
Section III Key Equations and Symbols 202
11 X-Ray Dosimetry in Projection Imaging and Computed Tomography . . . . . . . . . . . . . . . . . 204
11 .0 Introduction 20411 .2 Monte Carlo Simulation 205
11 .3 The Physics of X-Ray Dose Deposition 206
11 .4 Dose Metrics 207
11 .5 Radiation Dose in Projection Radiography 209
11 .6 Radiation Dose in Fluoroscopy 211
11 .7 Radiation Dose in Computed Tomography 212
11 .8 Dose Reporting Software and Dose Registries 216
11 .9 Diagnostic Reference Levels and Achievable Doses 217
11 .10 Summary—Typical Effective Doses For Radiographic Procedures 217
Section II Questions and Answers 218
Section III Key Equations and Symbols 222
12 Magnetic Resonance Basics: Magnetic Fields, Nuclear Magnetic
Characteristics, Tissue Contrast, Image Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
12 .1 Magnetism, Magnetic Fields, and Magnetic Properties of Materials 225
12 .2 MR System 227
12 .3 Magnetic Resonance Signal 229
12 .4 Magnetization Properties of Tissues 230
12 .5 Basic Acquisition Parameters 233
12 .6 Basic Pulse Sequences 234
12 .7 MR Signal Localization 242
12 .8 “K-Space” Data Acquisition and Image Reconstruction 245
12 .9 MR Image Characteristics 247
Section II Questions and Answers 249
Section III Key Equations, Symbols, Quantities, and Units 255
13 Magnetic Resonance Imaging: Advanced Image Acquisition Methods, Artifacts,
Spectroscopy, Quality Control, Siting, Bioeffects, and Safety . . . . . . . . . . . . . . . . . . . . . . . . 257
13 .0 Introduction 257
13 .1 Image Acquisition Time 257
13 .2 Fast Imaging Techniques 258
13 .3 Signal from Flow 260
13 .4 Perfusion and Diffusion Contrast Imaging 262
13 .5 Other Advanced Techniques 265
13 .6 MR Artifacts 267
13 .7 Magnet Siting and Quality Control 272
13 .8 MR Bioeffects and Safety 274
Section II Questions and Answers 277
Section III Key Equations and Symbols 281
14 Ultrasound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283
14 .0 Introduction 283
14 .1 Characteristics of Sound 283
14 .2 Interactions of Ultrasound with Tissues 285
14 .3 Ultrasound Transducers 286
14 .4 Ultrasound Beam Properties 289
14 .5 Image Data Acquisition and Processing 292
14 .6 Image Acquisition 294
14 .7 Image Quality, Storage, and Measurements 300
14 .8 Doppler Ultrasound 300
14 .9 Ultrasound Artifacts 305
14 .10 Ultrasound System Performance and Quality Assurance 309
14 .11 Acoustic Power and Bioeffects 310
Section II Questions and Answers 312
Section III Key Equations and Symbols 317
SECTION III: Nuclear Medicine ................................................. 319
15 Radioactivity and Nuclear Transformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321
15 .0 Introduction 321
15 .1 Definitions 321
15 .2 Nuclear Transformation 323
Section II Questions and Answers 327
Section III Key Equations and Symbols 330
16 Radionuclide Production, Radiopharmaceuticals, and Internal Dosimetry . . . . . . . . . . . . . 331
16 .0 Introduction 331
16 .1 Radionuclide Production 331
16 .2 Radiopharmaceuticals 337
16 .3 Internal Dosimetry 340
16 .4 Regulatory Issues 344
Section II Questions and Answers 34717 Radiation Detection and Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360
17 .0 Introduction 360
17 .1 Types of Detectors and Basic Principles 360
17 .2 Gas-Filled Detectors 363
17 .3 Scintillation Detectors 366
17 .4 Semiconductor Detectors 370
17 .5 Pulse Height Spectroscopy 373
17 .6 Nonimaging Detector Applications 377
17 .7 Counting Statistics 381
Section II Questions and Answers 386
Section III Key Equations and Symbols 393
18 Nuclear Imaging—The Gamma Camera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394
18 .0 Introduction 394
18 .1 Planar Nuclear Imaging: The Anger Scintillation Camera 394
18 .2 Computers in Nuclear Imaging 400
Section II Questions and Answers 403
Section III Key Equations and Symbols 409
19 Nuclear Tomographic Imaging—Single Photon and Positron Emission
Tomography (SPECT and PET) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 411
19 .0 Introduction 411
19 .1 Focal Plane Tomography in Nuclear Medicine 411
19 .2 Single-Photon Emission Computed Tomography 411
19 .3 Positron Emission Tomography 419
19 .4 Dual Modality Imaging—PET/CT and PET/MRI 424
19 .5 Advances in PET Imaging 426
19 .6 Clinical Aspects, Comparison of PET and SPECT, and Dose 427
Section II Questions and Answers 429
Section III Key Equations and Symbols 437
SECTION IV: Radiation Biology and Protection ................................... 439
20 Radiation Biology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441
20 .0 Introduction 441
20 .1 Interaction of Radiation with Cells and Tissues 441
20 .2 Molecular and Cellular Response to Radiation 442
20 .3 Tissue and Organ System Response to Radiation 446
20 .4 Whole Body Response to Radiation: The Acute Radiation Syndrome 447
20 .5 Radiation-Induced Carcinogenesis 449
20 .6 Hereditary Effects of Radiation Exposure 456
20 .7 Radiation Effects In Utero 456
20 .8 Radiation Risk Communications 457
Section II Questions and Answers 458
21 Radiation Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465
21 .0 Introduction 465
21 .1 Sources of Exposure to Ionizing Radiation 465
21 .2 Personnel Dosimetry 466
21 .3 Radiation Detection Equipment in Radiation Safety 467
21 .4 Fundamental Principles and Methods of Exposure Control 467
21 .5 Structural Shielding of Imaging Facilities 468
21 .6 Radiation Protection in Diagnostic and Interventional X-Ray Imaging 468
21 .7 Radiation Protection in Nuclear Medicine 469
21 .8 Regulatory Agencies and Radiation Exposure Limits 469
21 .9 Prevention of Errors 471
21 .10 Management of Radiation Safety Programs 471
21 .11 Imaging of Pregnant and Potentially Pregnant Patients 471
21 .12 Medical Emergencies Involving Ionizing Radiation 472
Section II Questions and Answers 473
Section III Key Equations, Symbols, Quantities, and Units 479
Section V: Appendices ....................................................... 481
A SI and Derived Units, Physical Constants, Prefixes, Definitions and Conversion
Factors, Geometry, and Roman and Greek Symbols Used in Medical Physics . . . . . . . . . . . 483
B Effective Doses, Organ Doses, and Fetal Doses from Medical Imaging
Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 489
C Radiopharmaceutical Characteristics and Dosimetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 496
Index 505