A simulation study on a PET detector using continuous LSO and large-area APDs

Improving the resolution and sensitivity of PET detectors has always been an area of major focus, and most recent attempts towards improving resolution tend to make use of smaller crystals that sacrifice sensitivity. Previously, a novel detector comprising of a single continuous slab of scintillator coupled with arrays of large area APDs onto both sides had been conceived, and a first prototype built. The first characterization of the prototype detector provided a spatial resolution of ~2.5 mm, somewhat worse than what was predicted by a previously developed analytical model. The limited electronic noise achievable was one of the main factors limiting detector performance. Hence, inorder to reduce the total electronic noise an evaluation of the various noise sources at the front-end was performed. Additionally, to better predict the performance of the detector a detailed Monte Carlo accounting for the light output and intrinsic resolution of the scintillator, the optical-photon transport mechanism, the quantum efficiency and gain of the APD, excess noise, and electronic noise contributions was developed. For interactions occurring at a fixed depth in the scintillator, the simulation predicts a FWHM spatial resolution of ~lmm.