Skip to main content.
__ __

Magnet Photo

Instrumentation for High Resolution Positron Emission Tomography

Abstract: Positron emission tomography (PET) is widely used for cancer detection, characterization, and monitoring treatment as well as in “preclinical” studies involving small animal models of human disease. In PET, metabolically active compounds are tagged with a positron emitting nuclide (e.g., 18F, 15O, 11C, 13N) and injected into a human or animal subject. Upon decay, the emitted positron annihilates with an electron resulting in two nearly back-to-back 511 keV annihilation photons. Photons detected in time-coincidence by the PET scanner localize the annihilation to a line through the object. From collection of a large number of these measurements (~107), the 3D spatial and temporal distributions of radiotracer can be reconstructed. In the past several decades the resolving power of PET instrumentation has improved from over 1 cm to 1 mm FWHM (and even below) in some cases. Nevertheless, the penetrating nature of 511 keV photons has rendered such improvements challenging and research on improved PET detectors remains vibrant with many approaches. One technique our group has been investigating is the use of silicon as a PET detector. While its use at first seems counterintuitive, the primary interaction of 511 keV photons in virtually all detectors used in PET is Compton scatter. As more conventional detectors based on high-Z scintillators such as LSO are made thicker to improve efficiency, scattered photons interact elsewhere in the scintillator resulting in significant mis-positioning with most scintillation light readout schemes. Although silicon holds some promise for developing specialized PET instruments having spatial resolution well below 1 mm FWHM there are significant challenges. Our experience silicon as well as with two “more conventional” approaches will be discussed for high resolution PET imaging in small animals and humans.
Speaker: Neal H. Clinthorne - University of Michigan
Speaker Bio: Neal Clinthorne is Research Professor of Radiology at the University of Michigan. For the past three decades, he has been involved with development of new techniques and systems for single photon emission tomography (SPECT), PET, and X-ray CT. SPECT work has included coded apertures, developments for the widely used technique of rotating gamma camera SPECT, and electronically collimated (i.e., “Compton camera”) systems. PET investigations include development of application-specific imaging probes and use of novel detectors. His X-ray CT work was spun off into Xoran Technologies, which he co-founded and is currently Chairman and VP.
Poster Link: Poster
Presentation: Presentation on 4/1/2009 (PDF)