基于GATE的小动物PET原型机仿真验证与性能评估

Simulation Verification and Performance Evaluation of Small Animal PET Prototype Using GATE

小动物正电子发射断层成像(PET)在药代动力学、新药研发、疗效评估等预临床研究中具有重要意义,但小动物PET的定量精度仍受限于探测器的空间分辨率与灵敏度的不足。为研发高性能的小动物专用PET探测器,提出"小孔径、大轴向跨度"的小动物PET搭建方案,并通过蒙特卡罗仿真技术,对该方案进行仿真验证与评估。该方案设计的原型机由60个晶体探测模块,分为5个连续的12边形探测环组成,其中心孔径与轴向跨度分别为102和125.4 mm,具备高达50.8°的光子最大接收角。采用GATE平台建立该原型机的仿真模型,并对其空间分辨率、计数性能(散射分数与等效噪声计数率)、探测灵敏度以及成像质量共4个性能进行预评估与分析。结果显示,该原型机的空间分辨率为1.62 mm,探测灵敏度为9.26%,散射分数为20.8,等效噪声计数率为2,256 kcps,总体性能与西门子Inveon PET系统相近,并在探测灵敏度及等效噪声计数率性能上分别取得21.36%以及35.14%的提升。基于GATE平台的仿真结果表明,采用"小孔径、大轴向跨度"的设计,能显著提升小动物PET系统的探测灵敏度,有望进一步提升小动物PET应用的定量精度。

Small animal positron emission tomography(PET)is of great significance in pre-clinical studies such as pharmacokinetics,new drug development,and therapeutic evaluation,but the quantitative accuracy of small animal PET is still limited by the lack of spatial resolution and sensitivity performance of the detector.In order to develop small animal-specific PET detectors with high-performance,this paper proposed a new construction solution with″small-diameter,large-axial-span″and used Monte Carlo simulation technology to verify and evaluate the prototype.The designed prototype consists of 60 crystal detection modules divided into five continuous twelve-sided detection rings.The central diameter and axial field of view of the scanner was102 mm and 125.4 mm,respectively,so it has a maximum photon reception angle of 50.8 degrees.A simulation model of the prototype was established using the GATE platform,and its spatial resolution,counting performance(scatter fraction and noise equivalent count rate),detection sensitivity and imaging quality were pre-evaluated and analyzed.Results showed that the prototype had a spatial resolution of 1.62 mm,a detection sensitivity of 9.26%,a scatter fraction of 20.8,and a noise equivalent count rate of 2256 kcps.The overall performance was similar to that of Siemens Inveon PET system,and the sensitivity and NECR performance was improved by 21.36%and 35.14%,respectively.The simulation results based on the GATE platform showed that the design of"small diameter and large axial field of view"could significantly improve the detection sensitivity of small animal PET systems and was expected to further improve the quantitative accuracy of small animal PET applications.