基于多距离系统矩阵叠加伽马图像重建方法研究  

Research on Gamma Image Reconstruction Method Based on Multi-distance System Matrix Superposition

作　　者：吴远 徐锋[1,2] 周义枞[1,2] 肖宇峰 郑玉来[3] WU Yuan;XU Feng;ZHOU Yicong;XIAO Yufeng;ZHENG Yulai(School of Information Engineering,Southwest University of Science and Technology,Mianyang 621010,China;Robot Technology Used for Special Environment Key Laboratory of Sichuan Province,Southwest University of Science and Technology,Mianyang 621010,China;China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]西南科技大学信息工程学院,四川绵阳621010 [2]西南科技大学特殊环境机器人技术四川省重点实验室,四川绵阳621010 [3]中国原子能科学研究院,北京102413

出　　处：《原子能科学技术》2024年第10期2211-2219,共9页Atomic Energy Science and Technology

基　　金：国家自然科学基金(12175187);龙山人才计划青年学者项目(181zx636)。

摘　　要：为了使伽马相机准确定位未知辐射场中多个放射源,本文基于最大似然期望最大化(maximum likelihood expectation maximization,MLEM)算法提出一种多距离系统矩阵叠加伽马图像重建算法。首先,通过蒙特卡罗模拟软件分析伽马相机结构,保证能够快速获取足够伽马光子计数;其次,根据放射源距离对探测器采集效率的影响,计算不同距离系统矩阵;最后,将多个系统矩阵叠加后估计放射源,最终得出放射源的位置信息。实验结果表明:该方法能对放射源快速定位;单源时具有较高的收敛性,多源时能准确定位多个放射源;相较于相关解码算法而言,本文方法具有更远的成像距离和较高的定位精度。As radioactive sources are increasingly used in scientific research,industry and other fields,radioactive sources are often lost due to improper management and control.Since gamma rays have higher penetrating power and longer action distance than α particles and β rays,they can affect a larger area and have radiation effects on various substances in the environment.Therefore,the search and positioning of radioactive sources has always been the focus of radioactive source search.Although gamma detection equipment can achieve relatively precise positioning of a single radioactive source,when there are multiple radioactive sources in the radiation environment,radioactive sources with weaker energy can easily be ignored.In order to enable the gamma camera to accurately locate multiple radioactive sources in the unknown radiation field at the same time,this paper proposed a multi-distance system matrix superposition gamma image reconstruction algorithm based on the maximum likelihood expectation maximization(MLEM) algorithm.First,Monte Carlo simulation software was used to build a gamma camera simulation,and the impact of different encoding patterns on detection efficiency and the impact of radioactive sources at different distances on detection performance were analyzed.In order to be as close to the actual situation as possible,the photoelectric effect,Compton scattering,electron pair effect and decay of the radioactive source were considered in subsequent simulation experiments,and the simulation structure is consistent with the gamma camera structure.Then,simulation was used to obtain projection data,and different distance system matrices were calculated based on the impact of radioactive source distance on detector collection efficiency.Besides,in order to simultaneously located multiple radioactive sources within different distance ranges,a new system matrix was formed by superimposing multiple system matrices with different distances,and then calculated with the projection data,and through continuous iteratio

关 键 词：放射源定位 伽马相机成像 最大似然期望最大化 蒙特卡罗模拟 多距离系统矩阵 

分 类 号：TL81[核科学技术—核技术及应用]