FPGA-based Data Acquisition System for SiPM Detectors

Positron Emission Tomography is a growing field with an increasing influence in nuclear medicine. Recent Time-of-Flight advancements have increased the cross-sectional image clarity and progression towards a miniature, silicon-based, photomultiplier has increased the resolution. As the photomultiplier size reduces, channel-count increases. Use of ASIC based Time-to-Digital converters with remote event processing is no longer viable due to the increasing cost and complexity. Instead, multichannel, FPGA based measurements with localized event processing is a must. Within this work, an FPGA based SiPM DAQ is presented with emphasis regarding the application of PET imaging. An introduction concerning PET concepts is included with a brief description of measurement techniques followed by a review of previous work with a detailed explanation of relevant methods. Next, an analysis of the problem covers specific implementation details and difficulties followed by a comparison of results to previous work. Use of a 28nm, Kintex 7 FPGA based DAQ is examined with implementation of a 32 channel, multichain averaged TDC with 15ps RMS resolution, 11ps average bin size, and less than 10ps of integral nonlinearity.