Wilson Keenan J, Alabd Roumani, Abolhasan Mehran, Safavi-Naeini Mitra, Franklin Daniel R
School of Electrical and Data Engineering, University of Technology Sydney, Sydney, NSW, Australia.
Australian Nuclear Science and Technology Organisation (ANSTO), Sydney, NSW, Australia.
Sci Rep. 2020 Jan 29;10(1):1409. doi: 10.1038/s41598-020-58208-y.
High-resolution arrays of discrete monocrystalline scintillators used for gamma photon coincidence detection in PET are costly and complex to fabricate, and exhibit intrinsically non-uniform sensitivity with respect to emission angle. Nanocomposites and transparent ceramics are two alternative classes of scintillator materials which can be formed into large monolithic structures, and which, when coupled to optical photodetector arrays, may offer a pathway to low cost, high-sensitivity, high-resolution PET. However, due to their high optical attenuation and scattering relative to monocrystalline scintillators, these materials exhibit an inherent trade-off between detection sensitivity and the number of scintillation photons which reach the optical photodetectors. In this work, a method for optimising scintillator thickness to maximise the probability of locating the point of interaction of 511 keV photons in a monolithic scintillator within a specified error bound is proposed and evaluated for five nanocomposite materials (LaBr:Ce-polystyrene, GdO-polyvinyl toluene, LaF:Ce-polystyrene, LaF:Ce-oleic acid and YAG:Ce-polystyrene) and four ceramics (GAGG:Ce, GLuGAG:Ce, GYGAG:Ce and LuAG:Pr). LaF:Ce-polystyrene and GLuGAG:Ce were the best-performing nanocomposite and ceramic materials, respectively, with maximum sensitivities of 48.8% and 67.8% for 5 mm localisation accuracy with scintillator thicknesses of 42.6 mm and 27.5 mm, respectively.
用于正电子发射断层扫描（PET）中伽马光子符合检测的离散单晶闪烁体高分辨率阵列成本高昂且制造复杂，并且在发射角度方面表现出固有的非均匀灵敏度。纳米复合材料和透明陶瓷是两类可供选择的闪烁体材料，它们可以制成大型整体结构，并且当与光学光电探测器阵列耦合时，可能为低成本、高灵敏度、高分辨率PET提供一条途径。然而，由于相对于单晶闪烁体，它们具有高光学衰减和散射，这些材料在检测灵敏度与到达光学光电探测器的闪烁光子数量之间表现出固有的权衡。在这项工作中，提出了一种优化闪烁体厚度的方法，以最大化在指定误差范围内定位511 keV光子在整体闪烁体中相互作用点的概率，并针对五种纳米复合材料（溴化镧：铈 - 聚苯乙烯、氧化钆 - 聚乙烯甲苯、氟化镧：铈 - 聚苯乙烯、氟化镧：铈 - 油酸和钇铝石榴石：铈 - 聚苯乙烯）和四种陶瓷（GAGG：铈、GLuGAG：铈、GYGAG：铈和LuAG：镨）进行了评估。氟化镧：铈 - 聚苯乙烯和GLuGAG：铈分别是性能最佳的纳米复合材料和陶瓷材料，对于5毫米定位精度，闪烁体厚度分别为42.6毫米和27.5毫米时，最大灵敏度分别为48.8%和67.8%。
