Position sensitive APDs for small animal PET imaging

In this paper, an 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 × 8 mm² have been characterized with single LSO crystals and arrays. Energy resolution of 19% (FWHM) for 511 keV γ-rays and coincidence timing resolution of ∼3 ns (FWHM) have been recorded with PSAPD coupled to 1 × 1 × 20 mm³ 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.