Medical Imaging

KRZYSZTOF INIEWSKI, PHD, manages R&D 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.

?The papers are very readable for serious physicists and electrical engineers who are focusing on electronics present in the health care field, as well as interested computer scientists and medical technicians.? (Computing Reviews , August 2009 )

• Preface xiiiAbout The Editor xvcontributors xviiI X-Ray Imaging and Computed Tomography 11 X-Ray and Computed Tomography Imaging Principles 3Krzysztof Iniewski1.1. Introduction to X-Ray Imaging 31.2. X-Ray Generation 61.3. X-Ray Interaction with Matter 91.4. X-Ray Detection 121.5. Electronics for X-Ray Detection 131.6. CT Imaging Principle 141.7. CT Scanners 151.8. Color X-Ray Imaging 171.9. Future of X-Ray and CT Imaging 18References 212 Active Matrix Flat Panel Imagers (AMFPI) for Diagnostic Medical Imaging Applications 23Karim Karim2.1. Introduction 232.1.1. Digital Imaging 232.1.2. Detection Schemes 242.1.3. Chapter Organization 272.2. Pixel Technology 272.2.1. Operation 272.2.1.1. Introduction 272.2.1.2. Operation 282.2.1.3. Charge Sensing or Voltage Sensing? 292.2.1.4. Gain and Linearity 302.2.1.5. Readout Rate 302.2.2. Fabrication 312.2.2.1. TFT Structure and Process 312.2.2.2. Nonoverlapped Electrode Process 322.2.2.3. Fully Overlapped Process 332.2.3. TFT Metastability 332.2.3.1. Physical Mechanisms 332.2.3.2. Positive Gate Bias Stress 372.2.3.3. Negative Gate Bias Stress 372.2.3.4. Effect of DC Bias Stress on Leakage Current 382.2.3.5. Pulse Bias Metastability 382.2.4. Electronic Noise 412.2.4.1. Thermal Noise 412.2.4.2. Flicker Noise 422.2.4.3. Noise in PPS Pixels 442.3. Recent Developments 452.3.1. Current Mode Active Pixel Sensor 462.3.1.1. Linearity 472.3.1.2. Gain 482.3.2. Application to Emerging Diagnostic Medical X-Ray Imaging Modalities 522.3.2.1. Dual-Mode Radiography/Fluoroscopy (R/F) 522.3.2.2. 3D Mammography Tomosynthesis 53References 553 Circuits for Digital X-Ray Imaging: Counting and Integration 59Edgar Kraft and Ivan Peric3.1. Introduction 593.1.1. Image Formation 593.1.2. X-Ray Detectors 603.1.2.1. Indirect Detectors 603.1.2.2. Direct Detectors 603.1.2.3. Hybrid Pixel Detectors 603.1.2.4. Readout Concepts for Hybrid Pixel Detectors 613.2. Circuit Implementation 613.2.1. The Photon Counter 623.2.2. The Integrator 633.2.3. The Feedback Circuit 663.2.3.1. Feedback and Signal Duplication 663.2.3.2. Static Leakage Current Compensation 673.2.3.3. Sampling 673.3. Experimental Results 683.3.1. Photon Counter Measurements 683.3.1.1. Dynamic Range 683.3.1.2. Electronic Noise 693.3.1.3. Noise Count Rate 693.3.2. Integrator Measurements 713.3.2.1. Dynamic Range 713.3.2.2. Noise Performance 713.3.3. Simultaneous Photon Counting and Integration 723.3.3.1. Total Dynamic Range 723.3.3.2. Pulse Size Reconstruction 743.3.3.3. Spectral Resolution 753.3.3.4. Spectral Hardening 753.4. Conclusion 76References 774 Noise Coupling in Digital X-Ray Imaging 79Jan Thim and Borje Norlin4.1. Characterization of Noise Problems in Detector Systems 794.2. Noise Mechanisms in Readout Electronics 824.2.1. Noise Models 834.2.1.1. Capacitive Coupling 844.2.1.2. Impact Ionization 854.2.2. Physical Properties 864.2.2.1. Power Distribution Networks 864.2.2.2. Substrates 884.3. Simulation Models in Various Design Levels 924.4. Readout Electronics Noise Coupling in Digital X-Ray Systems 934.4.1. Noise Coupling Effects on the Design Example System 94References 97II Nuclear Medicine (Spect and Pet) 1015 Nuclear Medicine: SPECT and PET Imaging Principles 103Anna Celler5.1. Introduction 1035.2. Nuclear Medicine Imaging 1045.3. Radiotracers 1055.4. Detection Systems 1075.5. Clinical SPECT Camera—Principles of Operation 1075.6. Clinical PET—Principles of Operation 1115.7. Comparison of Small Animal Scanners with Clinical Systems 1145.8. Electronic Collimation Principle and Compton Camera 1165.9. Hybrid SPECT–CT and PET–CT Systems 1175.10. Physics Effects Limiting Quantitative Measurement 1175.11. Tomographic Reconstruction Methods 1185.11.1. Filtered Back-Projection Reconstruction 1185.11.2. Iterative Reconstruction Algorithms 1195.12. Dynamic Imaging 1215.13. Quantitative Imaging 1225.14. Clinical Applications 123References 1246 Low-Noise Electronics for Radiation Sensors 127Gianluigi de Geronimo6.1. Introduction: Readout of Signals from Radiation Sensors 1276.2. Low-Noise Charge Amplification 1296.2.1. Input MOSFET Optimization 1296.2.2. Adaptive Continuous Reset 1356.3. Shaping and Baseline Stabilization 1386.3.1. High-Order Shaping 1396.3.2. Output Baseline Stabilization—The Baseline Holder 1466.4. Extraction 1506.4.1. Single- and Multiamplitude Discrimination 1506.4.2. Peak- and Time-Detection: The Multiphase Peak Detector 1526.4.3. Current-Mode Peak Detector and Digitizer 1586.5. Conclusions 160Acknowledgments 160References 160III Ultrasound Imaging 1657 Electronics for Diagnostic Ultrasound 167Robert Wodnicki, Bruno Haider, and Kai E. Thomenius7.1. Introduction 1677.2. Ultrasound Imaging Principles 1687.2.1. Ultrasound Scanning 1697.2.1.1. Sector Scan Probes 1707.2.1.2. Linear Scan Probes 1707.2.1.3. Curved Array Probes 1707.2.1.4. Compound Imaging 1717.2.2. Understanding Ultrasound Images 1717.2.2.1. Ultrasound Tissue Phantom 1717.2.2.2. Diagnostic Images 1727.2.3. Ultrasound Beam Formation 1727.2.3.1. Focusing and Steering 1727.2.3.2. Translation of the Aperture 1737.2.3.3. Transmit Beam Formation 1737.2.3.4. Receive Beam Formation 1737.2.4. Ultrasound Transmit/Receive Cycle 1747.2.5. Imaging Techniques 1757.2.5.1. Apodization or Weighting 1757.2.5.2. Dynamic Focusing 1767.2.5.3. Multiline Acquisition 1777.2.5.4. Codes 1787.2.5.5. Doppler Imaging 1787.2.5.6. Harmonic Imaging 1797.2.6. Image Quality Performance Parameters 1797.2.6.1. Reflection 1797.2.6.2. Absorption 1797.2.6.3. Resolution 1807.2.6.4. Dynamic Range 1817.2.6.5. Speckle 1827.2.7. Ultrasound Imaging Modalities 1827.3. The Ultrasound System 1837.3.1. Transducers 1837.3.2. High-Voltage Multiplexer 1847.3.3. High-Voltage Transmit/Receive Switch 1847.3.4. High-Voltage Transmitters 1847.3.5. Receive Amplifier and Time Gain Control 1857.3.6. Analog-to-Digital Converter and Beamformer 1857.3.7. Signal and Image-Processing 1857.4. Transducers 1857.4.1. Acoustic Characteristics 1867.4.2. Transducer Performance Characteristics 1877.4.3. Design and Modeling 1897.4.3.1. Electrical Impedance Models 1897.4.4. Alternative Transducer Technologies 1907.5. Transmit Electronics 1927.5.1. High-Voltage CMOS Devices 1927.5.2. Transmit/Receive (T/R) Switch 1947.5.3. High-Voltage Pulsers 1957.5.3.1. Unipolar and Trilevel Pulsers 1957.5.3.2. Multilevel Pulsers 1977.5.3.3. High-Voltage Multiplexers 1997.5.3.4. Tuning 2017.6. Receive Electronics 2017.6.1. Front-End Receive Signal Chain 2017.6.2. Low-Noise Preamplifier 2027.6.3. Time Gain Control Amplifier 2027.6.4. Analog-to-Digital Converter 2037.6.5. Power Dissipation and Device Integration 2037.7. Beam-Forming Electronics 2047.7.1. Digital Beam Formers 2047.7.2. Analog Beam Formers 2057.7.3. Hybrid Beam Formers 2067.7.4. Reconfigurable Arrays 2067.8. Miniaturization 2077.8.1. Portable Systems 2087.8.1.1. Tablet and Handheld Style Units 2097.8.1.2. Laptop-Style Units 2097.8.2. Transducer-ASIC Integration Strategies 2097.8.2.1. Co-integrated Single-Chip Devices 2107.8.2.2. Highly Integrated Multichip Devices 2117.8.3. Challenges to Effective Miniaturization 2127.9. Summary 214Acknowledgments 214References 214IV Magnetic Resonance Imaging 2218 Magnetic Resonance Imaging 223Piotr Kozlowski8.1. Introduction 2238.2. Nuclear Magnetic Resonance (NMR) 2268.2.1. Interaction of Protons with Magnetic Fields 2288.2.2. Macroscopic Magnetization and T1 Relaxation 2298.2.3. Rotating Frame and Resonance Condition 2308.2.4. T2 Relaxation and Bloch Equations 2348.2.5. Signal Reception, Free Induction Decay, and Spin-Echo 2378.2.6. Chemical Shift and NMR Spectroscopy 2408.3. Magnetic Resonance Imaging (MRI) 2428.3.1. Spatial Localization 2428.3.1.1. Slice Selection 2448.3.1.2. Frequency Encoding 2468.3.1.3. Phase Encoding 2488.3.2. k-Space 2508.3.3. Basic MRI Techniques 2528.3.3.1. Spin Echo 2538.3.3.2. Gradient Echo 2568.3.4. Signal and Noise in MRI 2578.3.5. Fast MRI Techniques 2608.3.5.1. RARE Imaging 2608.3.5.2. Steady-State Magnetization Imaging 2628.3.5.3. Echo Planar Imaging 2668.3.5.4. Other Fast Imaging Techniques 2698.3.6. Magnetic Resonance Spectroscopy (MRS) 273References 2809 MRI Technology: Circuits and Challenges for Receiver Coil Hardware 285Nicola De Zanche9.1. Introduction 2859.1.1. The MRI System 2859.1.2. Typical RF Receive Coil Array 2879.2. Conductorless Signal Transmission 2889.2.1. Possible Implementations 2899.2.1.1. Analog Transmission over Optical Fiber 2899.2.1.2. Wireless Analog Transmission 2909.2.1.3. Digital Transmission over Optical Fiber 2909.2.1.4. Wireless Digital Transmission 2909.2.2. General Issues 2919.2.3. Power Use and Delivery 2919.2.4. Low-Power Alternatives to PIN Diodes 2929.3. On-board Data Compression: The Scaleable, Distributed Spectrometer 2949.3.1. On-Coil Detection and Demodulation 2949.3.2. Online Data Pre-processing: Array Compression, Virtual Arrays, and Preconditioning 2979.4. Conclusion 299References 299Index 303