A flexible data acquisition module for high resolution PET camera

A prototype FPGA based fully digital data acquisition system for a positron emission tomography using LSO-crystals is described. Early digitization by sampling with free running ADCs provides accurate time stamps and energy estimates via optimum filters. The system is self-calibrating by running in two modes: calibration and production mode with widely different computational requirements well suited for modern FPGA implementation (software and firmware). In calibration mode the system uses a software, non-optimized, approach to determine signal and noise parameters. In the production mode, however, a minimized software part is used for monitoring and control. In this mode a major part of the FPGA (currently Xilinx Virtex II Pro) fabric implements an optimized systolic pulse processor algorithm. While the software part used a client server model for Ethernet communication with a controlling PC the main data path to the coincidence processor is dedicated point to point, with a minimized protocol overhead