基于GAGG闪烁体探测器康普顿相机角分辨率误差来源分析

基于Geant4模拟平台搭建了一个由2层6×6位置灵敏的cerium-doped gadolinium aluminum gallium garnet (GAGG(Ce))闪烁体探测器阵列组成的康普顿相机；从理论上分析了探测器的几何因素、能量分辨率和材料多普勒效应对康普顿相机角分辨率的影响；散射角为5°~90°时，角分辨率<10°．模拟条件:采集了仅考虑几何因素、能量分辨率与多普勒效应，以及综合考虑这3种误差来源等情况的符合数据，并用滤波反投影算法进行图像重建．当2层探测器距离为6.0~16.0 cm时，几何因素是影响角分辨率的主要误差来源，能量分辨率次之，多普勒效应贡献最小． 

Angular resolution error analysis of a Compton cameras based on GAGG scintillator detector

A Compton camera consisted of two layers of 6×6 position sensitive cerium-doped gadolinium aluminum gallium garnet (GAGG(Ce)) scintillators was simulated using Geant4．The dependence of angular resolution of such a Compton camera on system geometry, detector energy resolution and Doppler effect as a function of scattering angle was analyzed theoretically．The overall angular resolution is better than 10° when the scattering angle is in the range of 5°~90°．Coincidence events was acquired under 5 different circumstances: ideal case with accurate position and energy detection without considering Doppler effect; only considering system geometry effect; only considering detector energy resolution effect; only considering Doppler effect; taking all the three effects into account．Images are reconstructed using a filtered back projection algorithm running on OpenCL platform when the layer distance of the Compton camera is between 6.0~16.0 cm．Results show that the system geometry effect is the main factor on the angular resolution for the Compton camera simulated．