医用人体正电子发射成像系统光子检测器的精密制造及实验研究

发布时间：2018-05-10 15:52

本文选题：改进型PET检测器 + 网格模具支撑晶体阵列　；参考：《华中科技大学》2015年硕士论文

【摘要】：高性能伽玛光子检测器是医用人体正电子发射成像系统的核心,检测器对伽马光子的有效探测是PET系统高质量成像的前提。目前常用的检测器设计采用“离散晶体阵列+网状玻璃光导+PMT阵列”的晶体阵列与PMT阵列间接耦合技术,受限于设计形式、制作工艺及硬件条件,传统医用PET检测器的解码准确性、能量分辨率和时间分辨率等仍有很大提升空间。针对传统检测器存在的不足,本文通过对“离散晶体+等高反光填充+网状光导”分光设计进行拓展,提出基于非等高高反光率内壁网格模具支撑晶体阵列,并采用油脂类光导的改进设计,使得晶体阵列和PMT阵列之间通过油脂材料实现直接耦合,有望大幅提高检测器的光输出效率,并使其分光解码更加均匀。非等高高反光率内壁网格模具支撑晶体阵列的精密制造是改进设计的关键。采用一种可实现无缝配合的拼装方法进行网格模具整体架构制造,在系列带缝金属薄片表面粘贴ESR反光膜形成高反光表面,再将其按“交错正交式网格拼接法”逐片拼接而成网状结构。研究薄片插缝加工精度的最优化设计,以及缝缝配合、缝面配合的装配精度,保证网格结构内腔接缝处的光密性,提高拼接结构的整体性,再向拼装完成的网格模具深孔内填入闪烁晶体即可完成非等高高反光率内壁网格模具支撑晶体阵列的精密制造。试制若干不同阵列规模和晶体尺寸的改进型检测器,并对其进行解码性能测试对比,结果显示其分光解码图峰谷指数是国外某高端PET系统同类型检测器的2.3倍(5.23比2.26),能量分辨率比联影PQS设计检测器模块好34%(10.8%比14.5%),验证了改进设计的可行性和优越性。
[Abstract]:High performance gamma photon detector is the core of medical positron emission imaging system. The effective detection of gamma photon by detector is the premise of high quality imaging of PET system. At present, the commonly used detector is the indirect coupling technology between the crystal array and the PMT array, which is based on the "discrete crystal array network glass photoconductive PMT array", which is limited by the design form, fabrication process and hardware conditions. The decoding accuracy, energy resolution and time resolution of the traditional medical PET detector are still greatly improved. Aiming at the shortcomings of the traditional detector, this paper extends the design of "discrete crystal with high reflectance filled with mesh", and proposes a new method to support the crystal array based on the non-equal high reflectivity inner wall mesh mold. The improved design of grease photoconductivity makes the direct coupling between crystal array and PMT array through grease material, which is expected to greatly improve the optical output efficiency of the detector, and make the division decoding more uniform. The key to improve the design is the precision manufacture of the crystal array supported by the non-equal high reflectivity inner wall mesh die. A seamless fitting method is used to fabricate the whole structure of the mesh die. The high reflective surface is formed by sticking ESR reflective film on the surface of a series of metal sheet with seam. Then according to the "staggered orthogonal mesh splicing method", one by one to form a mesh structure. This paper studies the optimum design of machining precision of thin piece insert joint, and the assembly accuracy of seam fit and joint surface fit, which ensures the light density of the joint in the inner cavity of the mesh structure, and improves the integrity of the splicing structure. The scintillation crystal can be filled in the deep hole of the mesh mold to complete the precision manufacture of the non-equal high reflectivity inner wall mesh mold supporting crystal array. A number of improved detectors with different array sizes and crystal sizes have been developed, and their decoding performance has been tested and compared. The results show that the peak-valley index of the spectroscopic decoding chart is 2.3 times that of the same type of detector in a foreign high-end PET system, and the energy resolution is better than that of the PQS detector module. The feasibility and superiority of the improved design are verified.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TH776

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