基于GAGG闪烁体探测器康普顿相机角分辨率误差来源分析

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

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.

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.