Patent ID: 8340377

Claim:
An event processing module for a medical imaging device, comprising: an Application Specific Integrated Circuit (ASIC) configured for receiving analog signals from at least one photomultiplier tube (PMT) and transmitting analog outputs, the ASIC comprising a Constant Fraction Discriminator (CFD); an Analog-to-Digital Converter (ADC) configured for continuously sampling the analog outputs and transmitting digital outputs; and a Field Programmable Gate Array (FPGA) configured to collect a number of samples of the digital output during a sampling period when triggered by the CFD; wherein the FPGA is further configured to determine the energy of the analog signals for the sampling period from the at least one PMT by subtracting a baseline value of the samples from a peak value of the samples, the peak value being determined by selecting a sub-set of one or more of the samples where the sub-set includes fewer than all of the samples having values above the baseline value such that fewer than all of the values above the baseline value are used for determining the energy, the sub-set being selected as the one or more samples taken only around a peak during the sampling period, and by averaging the one or more samples of the sub-set, and the baseline value is determined as an average of at least one sample taken only around a beginning or end of the sampling period, the at least one sample taken only around the beginning or end of the sampling period being taken from the samples during the sampling period triggered by the CFD and not from any samples outside of the sampling period for which the energy is determined; and wherein the FPGA is configured to detect pileup and reject events corresponding to the detected pileup, a pileup being detected if the current baseline value exceeds a moving baseline value average over a number of previous pulses by more than a predetermined threshold value.