Novel methods of resolving energy and 3D positions of interactions in monolithic scintillator plates

We propose methods of direct calculation of 3D position of mono-energetic interaction events in monolithic scintillator plates. The scintillator plate is coupled to an array of photodetectors on one side only, using the sum of signals of a few photodetectors consisting of the subset of the array containing the event. The advantage of incorporating fewer photodetectors to resolve an event allows other subsets of photodetectors in the array to resolve different events simultaneously, thus improving the count rate. The energy filtration was performed by examining the locus of events in the plane of resolved energy versus resolved depth of interaction. Events of unwanted energy fall outside of a pre-defined energy window of interest, or the physical boundaries of the scintillator. We also developed an adaptive centroid method that takes into account the already resolved depth of interaction (DOI) to resolve X-Y position of events. Monte-Carlo simulation was used to evaluate the performance of the proposed method in a scintillator slab (10 mm × 10 mm × 100 mm LYSO), readout by a 3×3 photodetector subset. Simulation of the proposed method showed promising high resolution capability for DOI and X-Y positioning, as well as energy filtration capability.