双层错位DOI脑PET探测器晶体厚度组合优化设计  

Optimization Design of Crystal Thickness Combination for Dual-layer-offset DOI Detector for Brain PET

作　　者：魏清阳 许书钰 戴甜甜[2] 吕振雷 许天鹏 江年铭 马天予[3] 刘亚强[3] WEI Qingyang;XU Shuyu;DAI Tiantian;LYU Zhenlei;XU Tianpeng;JIANG Nianming;MA Tianyu;LIU Yaqiang(Beijing Engineering Research Center of Industrial Spectrum Imaging,School of Automation and Elecstrical Engineering,University of Science and Technology Beijing,Beijing 100083,China;Department of Radiation Oncology,China-Japan Friendship Hospital,Beijing 100029,China;Department of Engineering Physics,Tsinghua University,Beijing 100084,China;Beijing Novel Medical Equipment Ltd.,Beijing 102206,China)

机构地区：[1]北京科技大学自动化学院北京市工业波谱成像工程技术研究中心,北京100083 [2]中日友好医院放射肿瘤科,北京100029 [3]清华大学工程物理系,北京100084 [4]北京永新医疗设备有限公司,北京102206

出　　处：《原子能科学技术》2020年第9期1704-1708,共5页Atomic Energy Science and Technology

基　　金：国家自然科学基金资助项目(11975044,11605008);中央高校基本科研业务费资助项目(FRF-TP-19-019A3)。

摘　　要：双层错位晶体阵列是正电子发射断层成像(PET)仪获取作用深度(DOI)信息的一种低成本且简便的方案。为获得晶体厚度最优组合方案,本文使用GATE软件进行蒙特卡罗仿真研究。模拟兼容核磁共振成像(MRI)的嵌入式脑PET,环内径345 mm,使用硅酸钇镥(LYSO)晶体,2层晶体总厚度20 mm,内层晶体从0 mm到10 mm共11种厚度(间隔1 mm);进行点源模拟实验,点源位于中心断层x轴上,偏移从x=0 cm到x=10 cm共6种情况(间隔2 cm)。计算中心点灵敏度;采用滤波反投影算法重建图像,评估径向空间分辨率。结果显示,双层晶体的设计相比于单层晶体灵敏度略有下降,但系统径向空间分辨率显著提高且其均匀性得到改善。随着内层晶体厚度的增大,视野平均径向空间分辨率先减小后增大,在内层晶体厚度为8 mm时达到最小。综上所述,所设计的双层错位DOI脑PET探测器晶体厚度最优组合方案为内层晶体厚度8 mm、外层晶体厚度12 mm。Dual-layer-offset crystal array is a low cost and simple scheme for positron emission tomography(PET)system to achieve depth of interaction(DOI)information.Different thickness combinations of two layer crystals influence system performances.Monte Carlo simulations using GATE toolkit were implemented to optimize the design by evaluating the performances of the system with different thickness combinations in this study.Eleven magnetic resonance imaging(MRI)compatible brain PET inserted systems with an inner diameter of 345 mm,dual layer LYSO of 20 mm total thickness and inner layer thickness varied from 0 mm to 10 mm with a step size of 1 mm were built.Six point sources in the x-axis of the center slice from x=0 cm to x=10 cm with an interval of 2 cm were simulated.The sensitivity at the center was calculated and the radial resolutions were evaluated using the reconstructed points by the filtered back projection algorithm.The results show that dual-layer crystal design has a slight sensitivity decrease,but can significantly improve the radial spatial resolution and the resolution uniformity compared with the single-layer design.With the thickness increase of the inner crystal,the average radial spatial resolution decreases and then increases,and achieves minimal at inner layer with a thickness of 8 mm.In conclusion,8 mm in the inner layer and 12 mm in the outer layer is the optimal design for the brain PET system with 20 mm dual-layer-offset crystal proposed in this study.

关 键 词：正电子发射断层成像 作用深度 双层错位 晶体厚度组合优化 

分 类 号：O572.21[理学—粒子物理与原子核物理]