A method for processing events in a medical imaging device may comprise the steps of receiving analog signals from at least one PMT into an Applied Specific Integrated Circuit (ASIC) comprising a Constant Fraction Discriminator (CFD) and transmitting analog outputs from the ASIC. Further, sampling the analog outputs continuously using an Analog to Digital Converter (ADC) and transmitting digital outputs; and collecting a number of samples of the digital output during a sampling period using a Field Programmable Gate Array (FPGA) when triggered by the CFD. The method may additionally determine the energy of the analog signals from the at lease one PMT by subtracting the peak value of each signal from the baseline value of each signal, wherein the peak value is determined as an average of at least one sample taken only around the peak during the sampling period, and the baseline value is determined as an average of at least one sample taken only around the beginning or end of the sampling period.