DEVELOPMENT OF CONTINUOUS DETECTORS FOR A HIGH-RESOLUTION ANIMAL PET SYSTEM

We propose a design for a high resolution, gamma-camera style detector that is suitable for use in a positron emission tomograph dedicated to small animal research. Through Monte Carlo simulation we modeled the performance of a detector composed of one 76.2 x 76.2 x 8 mm thick LSO crystal coupled to a 3 '' square position sensitive photomultiplier tube (PS-PMT). We investigated the effect of optical coupling compounds, surface treatment and depth of interaction on the quantity (efficiency) and distribution (spread) of scintillation photons reaching the photocathode. We also investigated linearization of the position response. We propose a PET system consisting of fourteen of these detectors in 2 rings, yielding a 16 cm diameter by 15 cm long tomograph. It would operate in 3-D mode subtending a 68% solid angle to the center. The expected spatial resolution is less than or equal to 2 mm, with a system efficiency of similar to 10% at the center (200 keV lower threshold) and a singles count rate capability of approximately 10(6) cps per detector.