Compact Design of an FPGA Based Data Acquisition (DAQ) System for an RF-penetrable TOF-PET Brain Dedicated Insert

With advanced PET system development, processing a high number of channels online is necessary and critical, especially for applications with one-to-one coupled crystals and silicon photomultipliers (SiPMs). We are developing an RF-penetrable TOF-PET brain dedicated insert with lutetiumyttrium oxyorthosilicate (LYSO) crystals one-to-one coupled to SiPMs. There are 768 crystal-SiPM channels per detector module, and a PET insert ring comprises 16 detector modules. A compact design to process 12288 channels with a designed 20 kcps singles count rate per channel in real-time is challenging. In this paper, we developed an FPGA-based data acquisition (DAQ) system using a commercial evaluation board and characterized its performance with two full detector modules; each having 768 crystal-SiPM channels. We achieved a global energy resolution of 11.46 ± 0.02% FWHM and a global coincidence time resolution of 224.47 ± 0.15ps FWHM over 1536 SiPM-crystal channels with DAQ online processing. All parameters including global energy resolution, global CTR, coincidence count rate, and random count rate changed less than 3% between offline processing and online DAQ processing.