基于Monte Carlo仿真的PEM探测器优化设计  

Optimization PEM designs based on Monte Carlo simulations

作　　者：汪梦蝶[1] 刘懿龙[1] 胡广书[1] 张辉[1] 

机构地区：[1]清华大学生物医学工程系,北京100084

出　　处：《清华大学学报（自然科学版）》2014年第8期1092-1097,共6页Journal of Tsinghua University(Science and Technology)

摘　　要：为了评估双平板正电子发射乳腺断层成像(positron emission mammography,PEM)系统中平板厚度对系统成像质量的影响,并对探测器中晶体厚度进行优化,该文基于GATE(the GEANT4application for tomographic emission)仿真平台,建立双平板正电子发射断层成像(positron emission tomography,PET)系统模型,在不同探测器厚度下进行Monte Carlo仿真,完成数据采集和图像重建,通过比较各系统灵敏度、图像空间分辨率以及病灶检测能力,得出随着晶体厚度的减小重建图像的空间分辨率提高,但系统灵敏度和病灶检测能力降低的结论。研究结果表明:使用厚度为10mm的硅酸钇镥(lutetium-yttrium oxyorthosilicate,LYSO)闪烁晶体时,沿着平板的长、短轴方向的图像空间分辨率受反应深度效应(depth of interaction,DOI)影响不大,均能达到较高的水平;另外,在该晶体厚度下,双平板系统灵敏度能达11%左右。在用该系统采集10min后的投影数据得到的重建图像中,能用肉眼从背景噪声中清晰地分辨出小体积、低活度的放射源病灶。因此,针对该文所设计的PEM系统,10mm为晶体的较优厚度,同时保证了足够的系统灵敏度和较小的DOI效应。The influence of the detector thickness in dual-plate positron emission mammography（PEM）on the reconstructed image quality was evaluated to optimize the crystal thickness.The evaluations used a dual-plate PET system model built on the GEANT4 Application for Tomographic Emission（GATE）platform.Monte Carlo simulations were conducted for various detector thicknesses to analyze the system performances.Comparisons of the system sensitivity,image spatial resolution and tumor detectability of different systems showed that thinner crystals tended to improve the spatial resolution but reduced the system sensitivity and tumor detectability.The spatial resolution along the two directions of the panel＇s width and length were both good for a 10 mm thick crystal and were not severely impacted by the depth of interaction（DOI）effect.The system sensitivity was about 11%.With10 min data acquisition,a small low concentration tumor source could be easily distinguished from the background in the reconstructed image.Consequently,10 mm was chosen as a optimal crystal thickness for the PEM system to achieve both higher system sensitivity and less DOI effect.

关 键 词：正电子发射乳腺断层成像系统(PEM) 晶体厚度 优化设计 图像质量 

分 类 号：R318.6[医药卫生—生物医学工程]