Optical simulation of a 9×9 LYSO block detector with PQS technology using GATE

Design of the light sharing mechanisms has a significant influence on the performance of PET block detector. Monte Carlo simulation plays an important role in PET detector design and optimization. In this work, GATE is used to simulate the transportation processes of gamma rays and scintillated optical photons in a PMT-based 9×9 L YSO block detector of a self-developed animal PET system. The aim of this work is to optimize the optical parameters of the block detector design. Scintillation photons are generated and transported in the L YSO crystal array and finally detected by the 4 PMTs. Based on 2D Anger logic, the position of the crystal from which optical photons originate is calculated from the number of optical photons detected by the 4 PMTs. Different simulation parameters such as crystal side and bottom roughness and optical coupling pattern between crystals and reflecting films are tested in the simulation and 2D-MAPs of the detector are obtained. By comparing the 2D-MAPs acquired, we conclude that crystal side surface roughness has a significant influence on PET detector performance and a relatively rougher crystal side surface is recommended for applications while the detector performance is not sensitive to crystal bottom surface roughness and optical coupling pattern between crystals and reflecting films is key parameter for PET detector design as it determines the amounts of light sharing. The developed method is feasible for facilitating PET detector design and performance prediction.