Experimental characterization of novel small animal PET detector modules based on scintillation crystal blocks read out by APD arrays

Minimizing dead space is one way to increase the detection efficiency of small-animal PET scanners. By using monolithic blocks of scintillating material (e.g. 20 mmtimes10 mmtimes10 mm LSO), loss of efficiency due to inter-crystal reflective material is minimized. Readout of such blocks can be performed by means of one or more avalanche photo-diode (APD) arrays optically coupled to the block. The primary event position and depth of interaction (DOI) information are derived from the measured distribution of the scintillation light over the APD array(s). We are studying the feasibility of such detector modules, both by simulation and by experiment. A 64-channel setup for testing the above type of detector modules has been developed. Experiments to verify the effect of crystal surface finish, detector geometry and reconstruction algorithm parameters on the spatial resolution have been carried out. The first results of these experiments are presented in this paper, and compared to simulation results. This research is conducted in collaboration with the Crystal Clear Collaboration (CCC)