FPGA-based fast gamma-ray time mark estimator for ultra-miniature endoscopic PET applications

The endoscopic time-of-flight positron emission tomography concept implemented in an ultrasonic probe requires an ultra-miniaturized optical sensor capable of detecting single and multiple photons with high timing resolution. Due to the extreme levels of miniaturization of the detector, the large amount of data, and the real time data processing requirements, it makes sense to include complex functions inside the detector head. This work presents the algorithms and implementations of data readout, reformatting, sorting and filtering, and estimating of the time mark on a tiny field programmable gate array (FPGA) with limited logic resources. This FPGA will be mounted inside the endoscopic detector head to accelerate the data processing and to reduce data transmission. A simulation and comparison of different time mark estimators, as well as the analysis of their implementation feasibility, are also presented.