High-Resolution PET

PET resolution in existing small animal imaging systems is currently limited by scintillator pixel size (~1 mm). Intrinsic limitations for a PET system include: pixel size, scintillator properties (i.e. physics processes that convert the gamma ray to observable scintillation light), positron range, and non-colinearity. Simulation work suggests that resolution of better than 0.5 mm should be obtainable before intrinsic factors such as Compton scattering in the scintillator are important limitations. (See Phys Med Biol 2005; 50: 179-195.) LSO arrays with 0.42 mm crystals (0.5 mm spacing) have been fabricated and used in a benchtop setup to obtain images (see J Nucl Med 2007; 48: 115-121). Semi-conductor detectors (Ge, CdTe/CZT, TlBr) are also being tested as an option to produce more finely pixelated gamma ray detectors than is achievable with scintillation crystals. We are focusing on CdTe strip detectors as a material for a small animal PET scanner with DOI capability.

[strip detector]
Orthogonal strip CdTe detector, 0.5 mm thick to allow for good timing performance.

[mounted detector]
Prototype detector mounted for testing.

presentation slides from 2006 IEEE NSS/MIC conference (San Diego, CA)