高分辨率小动物Micro Insert PET系统的模拟研究  

Simulation study of high-resolution Micro Insert PET imaging system

作　　者：尹永智[1] 李梅春[1] 王慧鹏[1] 姚丽萍[1] 叶征乾 

机构地区：[1]兰州大学核科学与技术学院,兰州730000

出　　处：《核技术》2014年第11期23-28,共6页Nuclear Techniques

基　　金：国家自然基金项目(No.11305083);兰州大学国家级大学生创新创业训练计划项目(No.201310730129)资助

摘　　要：在西门子Micro PET小动物成像系统中接入高分辨率的Insert探测器环,组成了Micro Insert PET系统,可以进一步提高小动物PET系统的图像分辨率。本文采用蒙特卡罗模拟软件GATE定义Focus-220小动物PET和Micro Insert两种系统,在同步仿真运算中,给出了三种类型的符合数据,即PET Scanner和PET Scanner之间的符合、PET Scanner和Insert之间的符合、Insert和Insert之间的符合。用滤波反投影算法重建了Na-22单点源模型、多点源模型、LZU模型的PET图像。其中,多点源模型的径向图像分辨率的仿真结果与美国华盛顿大学的Micro Insert实验数据,在忽略正电子射程、非线性效应项以及噪声等的贡献下,两者符合得很好。研究表明,使用Micro Insert系统能够将小动物PET系统的图像分辨率提高到亚毫米水平。Background：Virtual-Pinhole PET is one of the methods to achieve high-resolution animal PET image, which suggests to integrate high-resolution detectors into existing PET scanner. Purpose： To validate the Virtual-Pinhole PET concept, we aimed to improve the image resolution of PET system to sub-millimeter range. Methods： Monte Carlo simulation code GATE （Geant4 Application for Emission Tomography） was applied to study the imaging resolution of a full ring Micro Insert system integrated with the SIEMENS MicroPET Focus-220. The track of gamma ray in both Insert detectors and PET Scanner detectors of Focus-220 was obtained simultaneously in one data taken. Three types of coincidence detections for gamma ray interactions in PET Scanner detectors and Insert detectors were selected, which represented coincidence detections between PET Scanner and PET Scanner （SS）, coincidence detections between PET Scanner and Insert （IS）, and coincidence detections between Insert and Insert （II）. The filtered back-projection （FBP） algorithm was employed to reconstruct the PET images of Na-22 point sources. Results： The image resolutions of GATE simulated data show 1.0-1.5 mm, 0.9-1.1 mm, and 0.5-0.9 mm at FWHM for SS, IS and II, respectively. These simulated results are kept good agreements with the experimental results of Micro Insert system obtained at Washington University. Conclusion： The image resolution of animal PET can be improved to sub-millimeter range by using Micro Insert PET system.

关 键 词：蒙特卡罗仿真 小动物PET MICRO Insert系统 图像重建 

分 类 号：R817[医药卫生—影像医学与核医学]