Upload
brucelee55
View
1.308
Download
1
Embed Size (px)
Citation preview
• Introduction to Medical Imaging– X-ray Computed Tomography (CT)– Nuclear Medicine
• Single Photon Emission Computer Tomography (SPECT)• Positron Emission Tomography (PET)
• VLSI Circuits for CT and SPECT
• Merging CT and SPECT hardware into one imaging technology.
• Highlights from CMOS Emerging Technologies workshop (www.cmoset.com) recently held in Vancouver
Kris Iniewski, Redlen Technologies
Circuits for CT Scanners and SPECT Gamma Cameras
About the Instructor
• Krzysztof (Kris) Iniewski is managing R&D at Redlen Technologies Inc., a start-up company in British Columbia. His research interests are in VLSI circuits for medical imaging.
• He is an editor of “VLSI Circuits for the NanoScale: Communications, Imaging and Sensing”, “Wireless Technologies: Circuits, Systems and Devices”, “Medical Imaging Electronics” and co-author of “Network Infrastructure and Architecture”.
• Dr. Iniewski has held management and research positions at the Universiy of Alberta (2004-2006), PMC-Sierra (1995-2003) and the University of Toronto (1988-1994). He has published over 100 research papers and holds 18 international patents.
• Kris is a Technical Chair for CMOS Emerging Technologies workshop (www.cmoset.com). He can be reached at [email protected]
Motivation for Medical Imaging
http://www.ecse.rpi.edu/censsis/
Healthcare Trends Drive Imaging Growth
http://www.ecse.rpi.edu/censsis/
Ultrasound Imaging
Visible InfraredMilli-
metre
Micro-
wave
and RF
THz gap
10 15Hz 10 14Hz 10 13Hz 10 12Hz 10 11Hz 10 10Hz
Ultra-
violetX Ray
10 16Hz10 17Hz
MRI
Nuclear medicine
10 18Hz10 19Hz
X Ray Imaging
100keV 10keV
TerahertzImaging
Frequency
Photonics ElectronicsOptical Imaging
MRI Optical Molecular Imaging Modalities
PET Imaging
µµµµ
+-
Variety of Techniques Available
http://www.ecse.rpi.edu/censsis/
CT vs. Nuclear Medicine (PET/SPECT)
• X-ray• Source/detector geometry• 3D computed tomography (CT)
• Nuclear Medicine (SPECT/PET)• Source of signal from within body
• 2D and 3D imaging
Source
Detector
Source
Detector
FLUOROSCOPY
Electron
Image Intensifier
TV PickupTube
XX--RayRay ANALOG IMAGE
LightTubeTube
MAMMOGRAPHY & RADIOGRAPHY PhosphorPhosphor Film
LightLightXX--RayRay
ANALOG IMAGE
TubeTube
XX--RayRay
XX--RayRay
Detector
TubeTube
XX--RayRayXX--RayRay
DIGITAL DETECTOR - FUTURE
DIGITAL IMAGE
CT/PET/SPECT Trends
X-Ray & Computed Tomography (CT)
Source: http://www.iwr.uni-heidelberg.de/groups/ngg/Tutorial/TutCT_121203_Lauritsch.pdf
CT Scanner - Principle
From Kris Iniewski, “X-ray and Computed Tomography Imaging Principles”, in Medical Imaging Electronics, K. Iniewski (Ed.), Wiley 2009.
CT Scanner - Reality
X-Ray Imaging to CT Imaging
• Standard X-ray’s limitations– 3D structures are collapsed
into 2D images– Low soft-tissue contrast,
great for bones– Not very quantitative
• X-ray CT– Take a large number of x-rays
at multiple angles– Calculate the 3D image
• Similar hardware to ordinary x-ray
• Image of a slice - extendable to 3D
• But, heavy computational load
http://www.ecse.rpi.edu/censsis/
SPECT Gamma Cameras
SPECT Diagnostic Example
• Left: SPECT scans of the brain of a three year old male near drowning patient shown shortly after the accident s howing decreased brain activity. The patient presented in a persistent vegetative state, and was pronounced blind with sev ere spasticity.
• Right: SPECT scans of the same child taken 9 months later demonstrating increased brain activity and blood fl ow following 120 hyperbaric oxygen treatments. The child was now alert, responsive, laughing, eating and drinking normally, walking, speaking bi-lingually, and had regained normal visi on.
SPECT vs. CT
• Unlike X-ray CT, SPECT produces 3-D images that relate an organ’s function.- better relay of extent of disease - reveals the course of the disease earlier.
• Simple process with immediate results. Less expensive than MRI or PET. Covered by insurance when brain injury is present.
• Unlike X-ray, there is an injection.
• Image quality can be decreased by patient movement (but new CZT based SPECT equipment has dramatically reduced measurement time).
Safety and Biohazards of CT/SPECT
• X-ray/Computer Tomography CT• Ionizing radiation (might be inducing cancer)
• Morbidity associated with contrast agents
• Nuclear Medicine (SPECT/PET)• Ionizing radiation (but very low dose)• Patient injection required
• Introduction to Medical Imaging– X-ray Computed Tomography (CT)– Nuclear Medicine
• Single Photon Emission Computer Tomography (SPECT)• Positron Emission Tomography (PET)
• VLSI Circuits for CT and SPECT
• Merging CT and SPECT hardware into one imaging technology.
• Highlights from CMOS Emerging Technologies workshop (www.cmoset.com) recently held in Vancouver
Kris Iniewski, Redlen Technologies
Circuits for CT Scanners and SPECT Gamma Cameras
Radiation Detection Principle
Radiation Detector Front End
http://www-physics.lbl.gov/~spieler/Heidelberg_Notes/
Charge Sensitive Amplifier (CSA)
CSA Calibration
Analog Signal Processing Chain
http://www-physics.lbl.gov/~spieler/Heidelberg_Notes/
Data Readout
Noise Spectrum
http://www-physics.lbl.gov/~spieler/Heidelberg_Notes/
Noise Equivalent Circuit
http://www-physics.lbl.gov/~spieler/Heidelberg_Notes/
X-Ray Detector Readout System
Pawel Grybos, “Detector Interface Circuits for X-ray Imaging”, in K. Iniewski (Ed.)Circuits for NanoScale – Communications, Imaging and Sensing, CRC Press 2008
Feedback Configurations
Pawel Grybos, “Detector Interface Circuits for X-ray Imaging”, in K. Iniewski (Ed.)Circuits for NanoScale – Communications, Imaging and Sensing, CRC Press 2008
Leakage Current Compensation
Pawel Grybos, “Detector Interface Circuits for X-ray Imaging”, in K. Iniewski (Ed.)Circuits for NanoScale – Communications, Imaging and Sensing, CRC Press 2008
DEDIX (Dual Energy Digital Imaging of X-ray)
Pawel Grybos, “Detector Interface Circuits for X-ray Imaging”, in K. Iniewski (Ed.)Circuits for NanoScale – Communications, Imaging and Sensing, CRC Press 2008
DEDIX – Single Channel
Pawel Grybos, “Detector Interface Circuits for X-ray Imaging”, in K. Iniewski (Ed.)Circuits for NanoScale – Communications, Imaging and Sensing, CRC Press 2008
Example: 8 keV photons from X-ray Tube
Pawel Grybos, “Detector Interface Circuits for X-ray Imaging”, in K. Iniewski (Ed.)Circuits for NanoScale – Communications, Imaging and Sensing, CRC Press 2008
Medipix 2 (256x256) – Pixel Readout
X. Llopart, M. Campbell, R. Dinapoli, D. San Segundo, E. Pernigotti, "Medipix2: a 64-k Pixel Readout Chip With 55-µm Square Elements Working in Single Photon Counting Mode,“IEEE Trans. Nucl. Sci., vol. 49, no. 5, 2002, pp. 2279 - 2283.
Medipix2 (256 x 256) – Chip Floorplan
X. Llopart, M. Campbell, R. Dinapoli, D. San Segundo, E. Pernigotti, "Medipix2: a 64-k Pixel Readout Chip With 55-µm Square Elements Working in Single Photon Counting Mode,“IEEE Trans. Nucl. Sci., vol. 49, no. 5, 2002, pp. 2279 - 2283.
Medipix2 Cell Layout
PILATUS Pixel Cell
Brönnimann et al.:"The Pilatus 1M Detector," J. Synchrotron Rad., 13, 2006, 120-130.
Common Circuit Requirements
• Signal amplification (LNA in Ultrasound and MRI, CSA in Nuclear Medicine and X-ray). Fighting noise sources and crosstalk is frequently the main battle in practical systems.
• Signal filtering (signal shaping in Nuclear Medicine). Signal multiplexing (have to deal with hundreds or thousands channels)
• ADC conversion (medical imaging operates at very low input SNR, analog signal processing is a must)
• Power dissipation is typically #1 challenge (difficulties in extracting heat).
• Signal processing of data close to a sensor beneficial, otherwise have to deal with Gb/s of data using a few Watts of power budge (if that).
• Sensor are very specialized and are much more important (and expensive!) than CMOS circuits
Power vs. ENC Trade-off
From Gianluigi De Geronimo, “Low-Noise Electronics for Radiation Sensors”, in MedicalImaging Electronics, K. Iniewski (Ed.), Wiley, 2008.
VA32 Chip (U of Michigan)
Practical Implementation Challenges
• Need to monitor temperature (on chip temperature sensors).
• Must calibrate sensor responses and non-linearities.
• Must deal with noise sources and digital cross-talk. Very difficult to de-bug at the system level.
• Have to deal with channel to channel non-uniformities.
• Would like to dissipate less than 50µW/channel.
• Must implement hundreds of channels per chip, thousands of channels would be even better.
• Would like to be able to self-test the circuit without the sensor stimuli (BIST).
MU
X
CSA Shaping PDChannel #1
CMLI/O
TempSensor
SPI
CSA Shaping PDChannel #2
CSA Shaping PDChannel #128
CtrlLogic
Bias
Practical CMOS Implementations
• FPGA Interface (SPI)
• Temperature Sensing
• Channel to Channel Uniformity
• On-chip Calibration
• Built-In SelftTesting (BIST)
• Low noise switching (CML/LVDS)
Pacific-128 datasheet, www.redlen.com
Pacific-128 Chip (Redlen)
X-Ray and CT Hardware Trends
• The fast front-end electronics for a large array of X-ray sensors should:– amplify and filter small signals from the each sensor element– perform analog to digital conversion– store the data on the integrated circuit in each channel
independently at the same time
• Complexity of the multi-channel mixed-mode integrated circuit implementation lie in the following areas:– power limitation– low level of noise– good matching performance and crosstalk effects
• Current challenges lie in detecting very low Xraydoses (there have been medical reports that CT scans are causing cancer related cell damage at the current doses used!)
• Introduction to Medical Imaging– X-ray Computed Tomography (CT)– Nuclear Medicine
• Single Photon Emission Computer Tomography (SPECT)• Positron Emission Tomography (PET)
• VLSI Circuits for CT and SPECT
• Merging CT and SPECT hardware into one imaging technology.
• Highlights from CMOS Emerging Technologies workshop (www.cmoset.com) recently held in Vancouver
Kris Iniewski, Redlen Technologies
Circuits for CT Scanners and SPECT Gamma Cameras
CT/SPECT Fusion
• Coupling SPECT with today’s high-powered CT scanners is going to propel the technology into a number of new research and clinical arenas—from in vivo small animal studies to CT angiography in the emergency department.
• New tracers already under testing specifically target cancers of the brain, thyroid, prostate, breast, lung, ovaries, kidneys, and liver, as well as heart and bone diseases and defects.
• With the advent of fusion imaging, nuclear medicine’s potential to diagnose and treat disease will advanced greatly offering numerous opportunities in clinical practice.
CT/SPECT Fusion
• SPECT/CT acquires both scans with the patient in the same position. Specialized registration software then reconstructs the data sets, adjusts for differences in format and scanner geometry, and fuses them into a single image.
• Grafting the high spatial resolution capabilities of today’s high-speed CT scanners with SPECT’shighly accurate definition of disease processes vastly enhances anatomical mapping and localization, moving the new hybrid directly into a wider range of clinical applications.
• Most significantly, CT attenuation correction greatly reduces the problems of distortion and degradation that typically occur with radionuclide-based methods.
CT/SPECT Fusion
• The existing SPECT/CT systems are made with two separated apparatus joined together axially and coaxially.
• Current research aims to enable a clinical system where both apparatus will use the same data acquisition system which is critical to achieve a perfect fusion of anatomical and metabolical images.
Integration (CT) and Counting (SPECT) Electronics
From Edgar Kraft, Ivan Peric, Circuits for Digital X-ray Imaging: Counting and Integration”, in Medical Imaging Electronics, K. Iniewski (Ed.), Wiley 2009.
From Edgar Kraft, Ivan Peric, Circuits for Digital X-ray Imaging: Counting and Integration”, in Medical Imaging Electronics, K. Iniewski (Ed.), Wiley 2009.
Integration (CT) and Counting (SPECT): Measurements
• Introduction to Medical Imaging– X-ray Computed Tomography (CT)– Nuclear Medicine
• Single Photon Emission Computer Tomography (SPECT)• Positron Emission Tomography (PET)
• VLSI Circuits for CT and SPECT
• Merging CT and SPECT hardware into one imaging technology.
• Highlights from CMOS Emerging Technologies workshop (www.cmoset.com) recently held in Vancouver
Kris Iniewski, Redlen Technologies
Circuits for CT Scanners and SPECT Gamma Cameras
CMOS Emerging Technologies workshop(www.cmoset.com)
• Held in Vancouver, Aug 5-7, 2008. Presentation slides available on-line.
• Related talks:
– Ralph Etienne-Cummings, John Hopkins U, Current Mode Active Pixels Sensors Make Focal-Plane Image Processing
– Jan Thim, Mid Sweden University, CMOS for Color X-Rays– Edoardo Charbon, EPFL, Single-Photon Imaging: the Next
Big Challenges– Karim Karim, U of Waterloo, CMOS Photon Counting Pixel
for Real-time Imaging of Palladium Seeds in Permanent Breast Seed Implantation
• Follow up meetings in Banff (Feb 18-20, 2009) and Vancouver (Sept 23-25, 2009). Speakers, volunteers and session chairs needed. Talk to me if interested, [email protected]