Effect of Scintillator Crystal Geometry and Surface Finishing on Depth of Interaction Resolution in PET Detectors - Monte Carlo Simulation and Experimental Results using Silicon Photomultipliers

Resolution of positron emission tomography (PET) systems benefits from information about depth of interaction (DOI) within scintillation crystals, particularly in small bore scanners or parallel plate detectors. In this investigation, the ability of the dual-ended readout detector module configuration to resolve DOI and crystal index was evaluated for a variety of detector pitches and light guide thicknesses to validate the dual-ended readout method. Experimental results with one-to-one coupling between saw-cut 2mm pitch LYSO scintillation crystals and silicon photomultipliers (SiPMs) achieved 2.1 mm DOI resolution. Monte Carlo simulations were used to investigate the effect of larger detector pitches and varied light guide thickness on the crystal index identification accuracy and DOI resolution for a pixilated crystal array in dual-ended readout configuration. It is reported that the accuracy in identifying a 2 mm scintillation crystal was > 80% for detector pitches < 6 mm and that DOI resolution was < 2 mm for all detector pitches and light guide thicknesses.