先进核医学影像探测器的位置和能量性能优化研究

发布时间：2018-01-25 17:11

本文关键词： 闪烁晶体探测器 CZT DOI 双端读出连续晶体　出处：《清华大学》2016年博士论文　论文类型：学位论文

【摘要】：以正电子发射断层成像(Positron Emission Tomography,PET)和单光子发射计算机断层成像(Single Photon Emission Computed Tomography,SPECT)为代表的核医学影像学是现代医学影像诊断的主要手段之一。伽马光子探测器是PET和SPECT成像系统的核心组成部分,优化探测器性能对提升成像系统综合性能和临床诊断价值具有重要意义。本论文旨在结合PET和SPECT影像系统实际临床应用,研究现代核医学影像探测器对伽马事件的位置和能量测量性能优化问题。能量分辨率对双核素SPECT成像具有重要价值。针对高能量分辨率CZT探测器在SPECT中的应用,重点研究CZT不完全电荷收集过程引入的低能尾部光子计数效应及其校正方法。基于商业CZT SPECT系统,提出CZT的尾部光子投影计数模型,开发了99mTc/123I双核素成像的散射和串扰校正方法,有效提高了图像定量精度。心肌模型实验99mTc图像的非透壁和透壁缺陷对比度由0.39和0.62分别提高到0.51和0.73;病人实验99mTc图像的心肌血池对比度由7.0提高到了63.6。测量作用深度(Depth of Interaction,DOI)信息是当前PET探测器技术的重点发展方向。本论文基于双端读出技术,研究了阵列式探测器的三维位置定位和能量性能优化方法。重点研究了不同晶体表面处理方式和DOI定位算法下探测器的DOI定位性能,提出了定量描述探测器能量性能的指标。最优的晶体表面处理方式为研磨晶体表面+镜面反射膜(能够获得优于2 mm的DOI分辨率和均衡的能量性能);线性算法和对数算法均能有效提取DOI信息并具有可类比的DOI性能。相比阵列式探测器,基于连续晶体的全三维位置定位技术是核医学影像探测器的近年研究热点之一。本论文研究了基于连续LYSO晶体和SiPM的全三维探测器技术。分别研究基于统计(Statistical-Based Positioning,SBP)和基于人工神经网络(Artificial Neural Network,ANN)的三维位置定位算法,实现了x/y和DOI方向分别约为2.0 mm和4.0 mm的定位分辨率。针对探测器读出通道数过多问题,提出基于Anger位置加权和基于主成分分析(Principal Component Analysis,PCA)的两种通道数压缩策略;利用SBP,x/y和DOI方向的定位分辨率分别约为2.6 mm和5.0 mm,与不压缩情况的定位能力可类比,从而提高了连续晶体探测器的工程应用价值。课题综合研究了核医学影像探测器的位置和能量性能优化方法,对于双核素SPECT成像定量精度提升以及PET和SPECT的空间分辨率提升均具有重要意义。
[Abstract]:Positron Emission Tomography was obtained by positron emission tomography. Pet) and single Photon Emission Computed Tomography. Nuclear medical imaging represented by SPECT is one of the main methods of modern medical imaging diagnosis. Gamma photon detector is the core component of PET and SPECT imaging system. The optimization of detector performance is of great significance to improve the comprehensive performance and clinical diagnostic value of imaging system. This paper aims to combine the practical clinical application of PET and SPECT imaging systems. This paper studies the optimization of the position and energy measurement performance of modern nuclear medical image detectors for gamma events. The energy resolution is of great value for binuclear SPECT imaging. Application in SPECT. The low energy tail photon counting effect introduced by CZT incomplete charge collection process and its correction method are studied. Based on the commercial CZT SPECT system, the tail photon projection counting model of CZT is proposed. The scattering and crosstalk correction methods for 99mTc / 123I binuclear imaging have been developed. The contrast of non-permeable and transmural defects in 99mTc images was improved from 0.39 and 0.62 to 0.51 and 0.73 respectively. The contrast of myocardial blood pool of 99mTc images was increased from 7.0 to 63.6. The depth of action was measured. DOI) information is the focus of the current PET detector technology. This paper based on dual-terminal readout technology. The three-dimensional position location and energy performance optimization of array detector are studied, and the DOI location performance of detector under different crystal surface treatment and DOI positioning algorithm is studied. The index of quantitatively describing the energy performance of the detector is presented. The best method of crystal surface treatment is the mirror reflection film on the ground crystal surface (the DOI resolution is better than 2 mm and the energy performance is equalized). Both the linear algorithm and the logarithmic algorithm can extract DOI information effectively and have comparable DOI performance. Full-3D position location technology based on continuous crystal is one of the hot research topics of nuclear medical image detector in recent years. In this paper, the full-3D detector technology based on continuous LYSO crystal and SiPM is studied respectively. Based on statistics (. Statistical-Based Positioning. SBP) and 3D position location algorithm based on artificial Neural Network (Ann). The location resolution of x / y and DOI is about 2.0 mm and 4.0 mm respectively. Two channel number compression strategies based on Anger position weighting and Principal component Analysis (PCA) are proposed. The location resolution in the direction of SBP x / y and DOI is about 2.6 mm and 5.0 mm, respectively, which can be compared with the localization ability in the case of no compression. Therefore, the engineering application value of continuous crystal detector is improved. The optimization method of position and energy performance of nuclear medical image detector is studied synthetically. It is of great significance to enhance the quantitative accuracy of binuclear SPECT imaging and the spatial resolution of PET and SPECT.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：R817

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