Medical imaging : principles, detectors, and electronics

This one-of-a-kind book addresses state-of-the-art integrated circuit design in the context of medical imaging of the human body. It explores new opportunities in ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), nuclear medicine (PET, SPECT), emerging detector technologies, circuit design techniques, new materials, and innovative system approaches.

Divided into four clear parts and with contributions from a panel of international experts, Medical Imaging systematically covers:

X-ray imaging and computed tomography-X-ray and CT imaging principles; Active Matrix Flat Panel Imagers (AMFPI) for diagnostic medical imaging applications; photon counting and integrating readout circuits; noise coupling in digital X-ray imaging

Nuclear medicine-SPECT and PET imaging principles; low-noise electronics for radiation sensors

Ultrasound imaging-Electronics for diagnostic ultrasonic imaging

Magnetic resonance imaging-Magnetic resonance imaging principles; MRI technology

Author Notes

Krzysztof Iniewski, PhD, manages RD chip development activities at Redlen Technologies. Previously, he was an associate professor in the electrical engineering and computer engineering department of the University of Alberta, where he conducted research on low-power wireless circuits and systems. His research interests are in VLSI circuits for medical and security applications. Dr. Iniewski has published over 100 international journal or conference papers, and holds eighteen international patents.

Krzysztof IniewskiKarim KarimEdgar Kraft and Ivan PericJan Thim and Borje NorlinAnna CellerGianluigi de GeronimoRobert Wodnicki and Bruno Haider and Kai E. ThomeniusPiotr KozlowskiNicola De Zanche

Preface	p. xiii
About the Editor	p. xv
Contributors	p. xvii
I X-Ray Imaging and Computed Tomography	p. 1
1 X-Ray and Computed Tomography Imaging Principles	p. 3
1.1 Introduction to X-Ray Imaging	p. 3
1.2 X-Ray Generation	p. 6
1.3 X-Ray Interaction with Matter	p. 9
1.4 X-Ray Detection	p. 12
1.5 Electronics for X-Ray Detection	p. 13
1.6 CT Imaging Principle	p. 14
1.7 CT Scanners	p. 15
1.8 Color X-Ray Imaging	p. 17
1.9 Future of X-Ray and CT Imaging	p. 18
References	p. 21
2 Active Matrix Flat Panel Imagers (AMFPI) for Diagnostic Medical Imaging Applications	p. 23
2.1 Introduction	p. 23
2.1.1 Digital Imaging	p. 23
2.1.2 Detection Schemes	p. 24
2.1.3 Chapter Organization	p. 27
2.2 Pixel Technology	p. 27
2.2.1 Operation	p. 27
2.2.1.1 Introduction	p. 27
2.2.1.2 Operation	p. 28
2.2.1.3 Charge Sensing or Voltage Sensing?	p. 29
2.2.1.4 Gain and Linearity	p. 30
2.2.1.5 Readout Rate	p. 30
2.2.2 Fabrication	p. 31
2.2.2.1 TFT Structure and Process	p. 31
2.2.2.2 Nonoverlapped Electrode Process	p. 32
2.2.2.3 Fully Overlapped Process	p. 33
2.2.3 TFT Metastability	p. 33
2.2.3.1 Physical Mechanisms	p. 33
2.2.3.2 Positive Gate Bias Stress	p. 37
2.2.3.3 Negative Gate Bias Stress	p. 37
2.2.3.4 Effect of DC Bias Stress on Leakage Current	p. 38
2.2.3.5 Pulse Bias Metastability	p. 38
2.2.4 Electronic Noise	p. 41
2.2.4.1 Thermal Noise	p. 41
2.2.4.2 Flicker Noise	p. 42
2.2.4.3 Noise in PPS Pixels	p. 44
2.3 Recent Developments	p. 45
2.3.1 Current Mode Active Pixel Sensor	p. 46
2.3.1.1 Linearity	p. 47
2.3.1.2 Gain	p. 48
2.3.2 Application to Emerging Diagnostic Medical X-Ray Imaging Modalities	p. 52
2.3.2.1 Dual-Mode Radiography/Fluoroscopy (R/F)	p. 52
2.3.2.2 3D Mammography Tomosynthesis	p. 53
References	p. 55
3 Circuits for Digital X-Ray Imaging: Counting and Integration	p. 59
3.1 Introduction	p. 59
3.1.1 Image Formation	p. 59
3.1.2 X-Ray Detectors	p. 60
3.1.2.1 Indirect Detectors	p. 60
3.1.2.2 Direct Detectors	p. 60
3.1.2.3 Hybrid Pixel Detectors	p. 60
3.1.2.4 Readout Concepts for Hybrid Pixel Detectors	p. 61
3.2 Circuit Implementation	p. 61
3.2.1 The Photon Counter	p. 62
3.2.2 The Integrator	p. 63
3.2.3 The Feedback Circuit	p. 66
3.2.3.1 Feedback and Signal Duplication	p. 66
3.2.3.2 Static Leakage Current Compensation	p. 67
3.2.3.3 Sampling	p. 67
3.3 Experimental Results	p. 68
3.3.1 Photon Counter Measurements	p. 68
3.3.1.1 Dynamic Range	p. 68
3.3.1.2 Electronic Noise	p. 69
3.3.1.3 Noise Count Rate	p. 69
3.3.2 Integrator Measurements	p. 71
3.3.2.1 Dynamic Range	p. 71
3.3.2.2 Noise Performance	p. 71
3.3.3 Simultaneous Photon Counting and Integration	p. 72
3.3.3.1 Total Dynamic Range	p. 72
3.3.3.2 Pulse Size Reconstruction	p. 74
3.3.3.3 Spectral Resolution	p. 75
3.3.3.4 Spectral Hardening	p. 75
3.4 Conclusion	p. 76
References	p. 77
4 Noise Coupling in Digital X-Ray Imaging	p. 79
4.1 Characterization of Noise Problems in Detector Systems	p. 79
4.2 Noise Mechanisms in Readout Electronics	p. 82
4.2.1 Noise Models	p. 83
4.2.1.1 Capacitive Coupling	p. 84
4.2.1.2 Impact Ionization	p. 85
4.2.2 Physical Properties	p. 86
4.2.2.1 Power Distribution Networks	p. 86
4.2.2.2 Substrates	p. 88
4.3 Simulation Models in Various Design Levels	p. 92
4.4 Readout Electronics Noise Coupling in Digital X-Ray Systems	p. 93
4.4.1 Noise Coupling Effects on the Design Example System	p. 94
References	p. 97
II Nuclear Medicine (Spect and Pet)	p. 101
5 Nuclear Medicine: SPECT and PET Imaging Principles	p. 103
5.1 Introduction	p. 103
5.2 Nuclear Medicine Imaging	p. 104
5.3 Radiotracers	p. 105
5.4 Detection Systems	p. 107
5.5 Clinical SPECT Camera-Principles of Operation	p. 107
5.6 Clinical PET-Principles of Operation	p. 111
5.7 Comparison of Small Animal Scanners with Clinical Systems	p. 114
5.8 Electronic Collimation Principle and Compton Camera	p. 116
5.9 Hybrid SPECT-CT and PET-CT Systems	p. 117
5.10 Physics Effects Limiting Quantitative Measurement	p. 117
5.11 Tomographic Reconstruction Methods	p. 118
5.11.1 Filtered Back-Projection Reconstruction	p. 118
5.11.2 Iterative Reconstruction Algorithms	p. 119
5.12 Dynamic Imaging	p. 121
5.13 Quantitative Imaging	p. 122
5.14 Clinical Applications	p. 123
References	p. 124
6 Low-Noise Electronics for Radiation Sensors	p. 127
6.1 Introduction: Readout of Signals from Radiation Sensors	p. 127
6.2 Low-Noise Charge Amplification	p. 129
6.2.1 Input MOSFET Optimization	p. 129
6.2.2 Adaptive Continuous Reset	p. 135
6.3 Shaping and Baseline Stabilization	p. 138
6.3.1 High-Order Shaping	p. 139
6.3.2 Output Baseline Stabilization-The Baseline Holder	p. 146
6.4 Extraction	p. 150
6.4.1 Single- and Multiamplitude Discrimination	p. 150
6.4.2 Peak- and Time-Detection: The Multiphase Peak Detector	p. 152
6.4.3 Current-Mode Peak Detector and Digitizer	p. 158
6.5 Conclusions	p. 160
Acknowledgments	p. 160
References	p. 160
III Ultrasound Imaging	p. 165
7 Electronics for Diagnostic Ultrasound	p. 167
7.1 Introduction	p. 167
7.2 Ultrasound Imaging Principles	p. 168
7.2.1 Ultrasound Scanning	p. 169
7.2.1.1 Sector Scan Probes	p. 170
7.2.1.2 Linear Scan Probes	p. 170
7.2.1.3 Curved Array Probes	p. 170
7.2.1.4 Compound Imaging	p. 171
7.2.2 Understanding Ultrasound Images	p. 171
7.2.2.1 Ultrasound Tissue Phantom	p. 171
7.2.2.2 Diagnostic Images	p. 172
7.2.3 Ultrasound Beam Formation	p. 172
7.2.3.1 Focusing and Steering	p. 172
7.2.3.2 Translation of the Aperture	p. 173
7.2.3.3 Transmit Beam Formation	p. 173
7.2.3.4 Receive Beam Formation	p. 173
7.2.4 Ultrasound Transmit/Receive Cycle	p. 174
7.2.5 Imaging Techniques	p. 175
7.2.5.1 Apodization or Weighting	p. 175
7.2.5.2 Dynamic Focusing	p. 176
7.2.5.3 Multiline Acquisition	p. 177
7.2.5.4 Codes	p. 178
7.2.5.5 Doppler Imaging	p. 178
7.2.5.6 Harmonic Imaging	p. 179
7.2.6 Image Quality Performance Parameters	p. 179
7.2.6.1 Reflection	p. 179
7.2.6.2 Absorption	p. 179
7.2.6.3 Resolution	p. 180
7.2.6.4 Dynamic Range	p. 181
7.2.6.5 Speckle	p. 182
7.2.7 Ultrasound Imaging Modalities	p. 182
7.3 The Ultrasound System	p. 183
7.3.1 Transducers	p. 183
7.3.2 High-Voltage Multiplexer	p. 184
7.3.3 High-Voltage Transmit/Receive Switch	p. 184
7.3.4 High-Voltage Transmitters	p. 184
7.3.5 Receive Amplifier and Time Gain Control	p. 185
7.3.6 Analog-to-Digital Converter and Beamformer	p. 185
7.3.7 Signal and Image-Processing	p. 185
7.4 Transducers	p. 185
7.4.1 Acoustic Characteristics	p. 186
7.4.2 Transducer Performance Characteristics	p. 187
7.4.3 Design and Modeling	p. 189
7.4.3.1 Electrical Impedance Models	p. 189
7.4.4 Alternative Transducer Technologies	p. 190
7.5 Transmit Electronics	p. 192
7.5.1 High-Voltage CMOS Devices	p. 192
7.5.2 Transmit/Receive (T/R) Switch	p. 194
7.5.3 High-Voltage Pulsers	p. 195
7.5.3.1 Unipolar and Trilevel Pulsers	p. 195
7.5.3.2 Multilevel Pulsers	p. 197
7.5.3.3 High-Voltage Multiplexers	p. 199
7.5.3.4 Tuning	p. 201
7.6 Receive Electronics	p. 201
7.6.1 Front-End Receive Signal Chain	p. 201
7.6.2 Low-Noise Preamplifier	p. 202
7.6.3 Time Gain Control Amplifier	p. 202
7.6.4 Analog-to-Digital Converter	p. 203
7.6.5 Power Dissipation and Device Integration	p. 203
7.7 Beam-Forming Electronics	p. 204
7.7.1 Digital Beam Formers	p. 204
7.7.2 Analog Beam Formers	p. 205
7.7.3 Hybrid Beam Formers	p. 206
7.7.4 Reconfigurable Arrays	p. 206
7.8 Miniaturization	p. 207
7.8.1 Portable Systems	p. 208
7.8.1.1 Tablet and Handheld Style Units	p. 209
7.8.1.2 Laptop-Style Units	p. 209
7.8.2 Transducer-ASIC Integration Strategies	p. 209
7.8.2.1 Co-integrated Single-Chip Devices	p. 210
7.8.2.2 Highly Integrated Multichip Devices	p. 211
7.8.3 Challenges to Effective Miniaturization	p. 212
7.9 Summary	p. 214
Acknowledgments	p. 214
References	p. 214
IV Magnetic Resonance Imaging	p. 221
8 Magnetic Resonance Imaging	p. 223
8.1 Introduction	p. 223
8.2 Nuclear Magnetic Resonance (NMR)	p. 226
8.2.1 Interaction of Protons with Magnetic Fields	p. 228
8.2.2 Macroscopic Magnetization and T1 Relaxation	p. 229
8.2.3 Rotating Frame and Resonance Condition	p. 230
8.2.4 T2 Relaxation and Bloch Equations	p. 234
8.2.5 Signal Reception, Free Induction Decay, and Spin-Echo	p. 237
8.2.6 Chemical Shift and NMR Spectroscopy	p. 240
8.3 Magnetic Resonance Imaging (MRI)	p. 242
8.3.1 Spatial Localization	p. 242
8.3.1.1 Slice Selection	p. 244
8.3.1.2 Frequency Encoding	p. 246
8.3.1.3 Phase Encoding	p. 248
8.3.2 k-Space	p. 250
8.3.3 Basic MRI Techniques	p. 252
8.3.3.1 Spin Echo	p. 253
8.3.3.2 Gradient Echo	p. 256
8.3.4 Signal and Noise in MRI	p. 257
8.3.5 Fast MRI Techniques	p. 260
8.3.5.1 RARE Imaging	p. 260
8.3.5.2 Steady-State Magnetization Imaging	p. 262
8.3.5.3 Echo Planar Imaging	p. 266
8.3.5.4 Other Fast Imaging Techniques	p. 269
8.3.6 Magnetic Resonance Spectroscopy (MRS)	p. 273
References	p. 280
9 MRI Technology: Circuits and Challenges for Receiver Coil Hardware	p. 285
9.1 Introduction	p. 285
9.1.1 The MRI System	p. 285
9.1.2 Typical RF Receive Coil Array	p. 287
9.2 Conductorless Signal Transmission	p. 288
9.2.1 Possible Implementations	p. 289
9.2.1.1 Analog Transmission over Optical Fiber	p. 289
9.2.1.2 Wireless Analog Transmission	p. 290
9.2.1.3 Digital Transmission over Optical Fiber	p. 290
9.2.1.4 Wireless Digital Transmission	p. 290
9.2.2 General Issues	p. 291
9.2.3 Power Use and Delivery	p. 291
9.2.4 Low-Power Alternatives to PIN Diodes	p. 292
9.3 On-board Data Compression: The Scaleable, Distributed Spectrometer	p. 294
9.3.1 On-Coil Detection and Demodulation	p. 294
9.3.2 Online Data Pre-processing: Array Compression, Virtual Arrays, and Preconditioning	p. 297
9.4 Conclusion	p. 299
References	p. 299
Index	p. 303

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Table of Contents