光导厚度对基于高分辨率LYSO和SiPM阵列PET探测器性能的影响  

Effects of light guide thickness on the performance of PET detectors consisting of high-resolution LYSO and SiPM array

作　　者：征云飞 李兰君[1] 邝忠华 王晓辉[2] 杨茜 桑子儒 任宁[2] 吴三 付鑫[2] 杨永峰[2] ZHENG Yunfei;LI Lanjun;KUANG Zhonghua;WANG Xiaohui;YANG Qian;SANG Ziru;REN Ning;WU San;FU Xin;YANG Yongfeng(College of Electrical Engineering, University of South China, Hengyang 421001, China;Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China)

机构地区：[1]南华大学电气工程学院,衡阳421001 [2]中国科学院深圳先进技术研究院,深圳518055

出　　处：《核技术》2018年第4期40-46,共7页Nuclear Techniques

基　　金：国家自然科学基金项目(No.81527804;No.11575285);广东省自然科学基金项目(No.2014A030312006);深圳市基础研究项目(No.JCYJ20160608153434110)资助~~

摘　　要：正电子发射计算机断层显像(Positron Emission Tomography,PET)是一种高灵敏和具有定量测量能力的分子影像方法,PET探测器通常由高探测效率的晶体阵列和位置灵敏或阵列光探测器组成,PET探测器的位置分辨率主要由晶体单元的大小和晶体分辨图的质量决定。使用现有小动物PET探测器常用的硅酸钇镥(Lutetium-yttrium Oyorthosilicate,LYSO)晶体阵列和硅光电倍增管(Silicon Photomultipliers,Si PM)阵列,系统地研究了晶体阵列和Si PM阵列之间光导的厚度对探测器晶体分辨图和能谱的影响。所使用的晶体阵列为12×12,单个晶体尺寸为0.89 mm×0.89 mm×10 mm,Si PM为日本滨松的4×4阵列,单元大小为3 mm×3 mm,间距为3.2 mm,光导使用厚度为0.5 mm、1.0 mm、1.5 mm、2.0 mm和2.5 mm的有机玻璃。实验结果表明:晶体分辨图的均匀性和对边缘晶体的分辨能力随着光导厚度的增加而改善,但随着光导厚度的增加,晶体分辨图中每个晶体单元的斑点大小增加,整个晶体分辨图的动态范围缩小。光导的使用几乎不改变晶体能谱的全能峰峰位和能量分辨率。综合以上因素,确定最佳的光导厚度为1.5 mm,本结果可对使用晶体截面约为1 mm×1 mm的晶体阵列和单元大小为3 mm×3 mm的Si PM阵列研发小动物PET探测器提供重要参考作用。[Background] Positron emission tomography（PET） is a highly sensitive and quantitative molecular imaging modality. PET detector usually consists of a high efficient scintillator array and a position sensitive photodetector or a photodetector array. The spatial resolution of a PET detector is mainly determined by the crystal size of the scintillator array and the quality of the flood histogram of the detector. [Purpose] This paper aims to study the effects of the thickness of the light guide used between the scintillator array and photodetector in the flood histogram and energy spectra of the detector by the lutetium-yttrium oxyorthosilicate（LYSO） scintillator array and silicon photomultiplier（Si PM） array most commonly used in current small animal PET scanners. [Methods] The scintillator array is 12×12 with a crystal size of 0.89 mm×0.89 mm×10 mm. A Hamamatsu 4×4 Si PM array with a 3 mm×3 mm pixel size and 0.2 mm gap between pixels is used. The light guide is made of plexiglass with thickness of 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm and 2.5 mm. [Results] The results show that the uniformity of the flood histogram and the capability of resolving the edge crystals improves as the thickness of the light guide increases. The spot size of each individual crystal in the flood histogram increases and the dynamic range of the flood histogram decreases as the thickness of the light guide increases. The light guide has almost no effect on the average photopeak amplitude and energy resolution of the crystal energy spectra. Overall light guide of 1.5 mm provides the best detector performance. [Conclusion] The results of this work provide guidance for developing small animal PET detector using LYSO array with a crystal cross section of about 1 mm×1 mm and Si PM array with a pixel size of 3 mm×3 mm.

关 键 词：PET探测器 位置分辨率 光导 晶体分辨图 能谱图 

分 类 号：TL99[核科学技术—核技术及应用]