UC Davis

In this paper, investigation of position sensitive avalanche photodiodes (PSAPDs) as optical detectors for reading out segmented scintillation arrays of LSO in high resolution PET modules is reported. PSAPDs with 8 x 8 mm(2) and 14 x 14 Turn 2 area have been characterized with single LSO crystals and arrays. Energy resolution of 19% (FWHM) for 511 keV gamma-rays and coincidence timing resolution of similar to3 ns (FWHM) have been recorded with PSAPD coupled to 1 x I x 20 mm(3) LSO detectors. Flood histogram studies have been successfully conducted by coupling multi-element element LSO arrays (1 mm pixels, 20 mm tall) to the PSAPDs. Finally, depth of interaction (DOI) resolution of <4.5 mm (FWHM) has been measured by coupling two PSAPDs on opposite ends of a 20 mm long LSO crystal with a I X 1 mm(2) cross section. Based on these results, PSAPDs appear to be promising for high resolution PET. An important advantage. of these PSAPDs is significant reduction in electronic readout requirements.