1 / 15

Very High Resolution Small Animal PET

Very High Resolution Small Animal PET. Don J. Burdette Department of Physics. What is PET?. Answer: Cancerous cells have a higher metabolism than normal cells, thus PET scans detect cancer.

garrett-duke
Download Presentation

Very High Resolution Small Animal PET

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Very High Resolution Small Animal PET Don J. Burdette Department of Physics

  2. What is PET? Answer: Cancerous cells have a higher metabolism than normal cells, thus PET scans detect cancer. Other Uses for PET include detection of Cardiovascular Disease, Alzheimer’s disease, Parkinson’s disease, epilepsy, and other neurological disorders. • PET stand for Positron Emission Tomography • It is a leading medical imaging technique (more than 200,000 PET scans in over 700 institutions performed last year in the US) • Unlike MRI and X-Ray (which image bodily structure) PET creates images of metabolic processes Question: Why is imaging metabolic processes important? Example of a PET image An image of damaged heart (left) compared to a normal heart (right). The damaged heart has undergone a heart attack. Single slice

  3. How does PET work? Photons Electron - + Radioactive Tracer Positron

  4. How does PET work? • Typical Resolution of human full body scans about 10mm • There exist other applications for PET technology outside human imaging

  5. Small Animal PET Systems Uses of Small Animal PET systems: • biomedical, pharmaceutical, and genetic manipulation research • Mice are used as human disease models • A single mouse can be used to tract disease development and treatment (Important for genetically altered specimens) Example of a Small Animal PET image Challenges for Small Animal PET: • Need resolution of less than 1mm • Lower doses, high efficiency Possible Solutions: Transgenic mouse showing cells with albumin gene switched on • smaller detection elements • higher efficiency detectors • Increase solid angle of the detector

  6. MicroPET R4 from University of Michigan’s PET center • Consists of 8 X 8 array of individual LSO scintillation crystals coupled to 64-channel PMT • 15 cm detection ring diameter • Typical System resolution = 1.8 mm • Image of two 1.1-1.2mm capillary tubes filled with Flourine-18 source

  7. Silicon Detectors Characteristics of ideal Silicon detector for use in PET: • Thick detector to increase efficiency (1mm compared to typical 0.3mm thickness) • Small detection pads for excellent spatial resolution • Custom made readout chips including an amplifier, and sample-hold switch • Chips have trigger logic to allow independent silicon operation Silicon Detector composed of an array of 32 X 16 pads 1mm thick by 1.4mm X 1.4mm in area • Small Detection Pixels yield excellent spatial resolution of the absorbed photons • Timing resolution of 200ns (Coincidence Window) Americium-241 spectrum collected by silicon detector

  8. Experimental Set-up In collaboration with the University of Michigan PC Silicon Detector Data Aquisition Module Coincidence Logic Intermediate Board Intermediate Board Collimated Source Si Trigger 1 Si Trigger 2 Si Signal Source Si Signal Mechanical Set-up Si Detector Si Detector

  9. Reconstructing the Data for a Simulated Disk Source Simple Back-Projection of the data (just drawing the lines) Fourier transforming this image into frequency space…

  10. Reconstructing the Data for a Simulated Disk Source • Blue line = unfiltered data • Green line = filtered data • The narrower the peak, the higher the resolution = sharper image Projection of previous image with and without filtering

  11. Reconstructing the Data for a Simulated Point Source Image of Disk Source after filtering and transforming back to position space

  12. Reconstructing the Data for a Simulated Disk Source Original Image Filtered Image

  13. Our small animal PET set-up Resolution of 0.7mm From microPET R4 set-up Resolution of 1.8mm Experimental Results Images of Flourine-18 source contained in two 1.1-1.2mm capillary tubes with a wall thickness of 0.2mm.

  14. Conclusion and Future Work • Our prototype Small Animal PET achieves a system resolution below the 1mm goal demonstrating the usefulness of silicon in Small Animal PET applications. Future Work includes: • Add a stack of silicon detectors to increase efficiency • Improve rate capabilities by decreasing coincidence window This can be accomplished by taking advantage of the Compton scattered photon and using a secondary detector with faster coincidence timing (Silicon timing 200ns coincidence window, timing from some scintillation crystals approach 60ns)

  15. References • Miles N. Wernick and John N. Aarsvold, editors. Emission Tomography: The Fundamentals of PET and SPECT. Elsevier, Acad Press, 2004. • Glenn F. Knoll. Radiation Detection and Measurement. John Wiley and Sons, Inc. 1989. • Christof Knoess. Performance evaluation of the Micropet R4 pet scanner of rodents. Eur J Nucl Med Mol Imaging, 2003. • Special Thanks to Neal Clinthorne, Klaus Honscheid, Harris Kagan, Sang-June Park, and Joseph Regensburger

More Related