Energy calibration of individual crystals in a LYSO pixelated array for microPET detection modules using Voronoi diagrams

Most small-animal positron emission tomography imaging systems nowadays use scintillator crystal arrays coupled to position-sensitive photomultiplier tubes (PS-PMT) as their detector modules. Individual crystal region identification to set tight energy thresholds has been introduced to reduce scatter and pileup events. In this work, we have used Voronoi diagrams to implement both tasks in a fast and efficient way for data analysis from a 20×20 LYSO crystal array coupled to Hamamatsu H8500 PS-PMT. This module forms part of a benchtop microPET system currently being developed at UNAM, Mexico. The results show that the use of individual crystal energy windows does not reduce image distortions, caused by pulse pileup, in 2-D data acquisition projections obtained with our system.