【摘要】 在PET探测器中,PMT的有效探测面积小于其外壳尺寸,造成相邻探测模组间存在缝隙,使得获得的数据存在缺失,降低了系统的灵敏度。通过在晶体与PMT之间加入梯形光导的方式可以填补缝隙,然而,光导的加入会致使系统的能量分辨率下降,在要求高能量分辨率的应用中会使得系统成像性能不足;并且,光导的加入也会增加系统成本。通过研究探测模组间缝隙对PET成像质量的影响,基于正在开发的μPET系统,对有光导和无光导两种探测器结构进行仿真建模并实现图像重建。通过分析比较两种结构下的重建图像质量,得出如下结论:当探测模组缝隙比例达17.56%时无光导结构仍能成像;有光导结构下的重建图像的信噪比优于无光导结构;无光导结构下,热源的对比度分数优于有光导结构,而冷源的对比度分数略逊于有光导结构。更多还原

【Abstract】 In the PET scanner,the size of PMT is bigger than its effective area,thus there are gaps between the adjacent detection modules.The gaps cause incomplete projection data and deteriorate sensitivity.The trapezoid light-guide is used to handle this problem.However,the light-guide decreases energy resolution and increases cost.In application with high energy resolution requirement,the imaging performance with light-guide is undesirable.In this work,we investigate the effect of gap between detection modules on PET imaging performance.We model two prototypical scanners with and without light-guide,respectively,for the developed μPET.Image reconstructions are performed for the two scanners.Based on the numerical analysis of the reconstructed images,we reach the conclusions as follows: Valid reconstructed images can be obtained with the gap size up to 17.56% of the PMT;the signal-to-noise ratio(SNR) with light-guide is higher;the percent contrast with light-guide is lower for hot source and higher for cold source.更多还原