A prototype detector for a novel high-resolution PET system: BazookaPET

We have designed and are developing a novel proof-of-concept PET system called BazookaPET. In order to complete the PET configuration, at least two detector elements are required to detect positron-electron annihilation events. Each detector element of the BazookaPET has two independent data acquisition channels. One side of the scintillation crystal is optically coupled to a 4 × 4 silicon photomultiplier (SiPM) array and the other side is a CCD-based gamma camera. Using these two separate channels, we can obtain data with high energy, temporal and spatial resolution data by associating the data outputs via several maximum-likelihood estimation (MLE) steps. In this work, we present the concept of the system and the prototype detector element. We focus on characterizing individual detector channels, and initial experimental calibration results are shown along with preliminary performance-evaluation results. We measured energy resolution and the integrated traces of the slit-beam images from both detector channel outputs. A photo-peak energy resolution of ~5.3% FWHM was obtained from the SiPM and ~48% FWHM from the CCD at 662 keY. We assumed SiPM signals follow Gaussian statistics and estimated the 2D interaction position using MLE. Based on our the calibration experiments, we computed the Cramer-Rao bound (CRB) for the SiPM detector channel and found that the CRB resolution is better than 1 mm in the center of the crystal.