Exploring the limits of PET resolution with a monolithic scintillator detector

We have built and evaluated a gamma-ray imaging detector for PET and simultaneous PET-MRI with the goal of providing sub-mm spatial resolution in all 3 dimensions. It consists of a solid slab of LYSO coupled to arrays of silicon photomultipliers (SiPMs) on both sides. The design is relatively cost-effective because it requires minimal mechanical processing of the scintillator, and because the photosensors are relatively large resulting in a small number of readout channels. Positioning algorithms employed include simple Anger centroid and a unique maximum likelihood approach with a measured system model which was developed for a previous generation APD-based detector. The design and construction of the detector, front-end electronics, data acquisition, and data processing methods are presented. The SiPM arrays are characterized and preliminary measures of energy, timing, and spatial resolution have been obtained, indicating promising performance.