Positron Emission Tomography (PET) reconstructed image signal-to-noise ratio (SNR) can be improved by including the 511 keV photon pair coincidence time-of-flight (TOF) information. The degree of SNR improvement from this TOF capability depends on the coincidence time resolution (CTR) of the PET system, which is essentially the variation in photon arrival time differences over all coincident photon pairs detected for a point positron source placed at the system center. The CTR is determined by several factors including the intrinsic properties of the scintillation crystals and photodetectors, crystal-to-photodetector coupling configurations, reflective materials, and the electronic readout configuration scheme. The goal of the present work is to build a novel TOF-PET system with 100 picoseconds (ps) CTR, which provides an additional factor of 1.5–2.0 improvement in reconstructed image SNR compared to state-of-the-art TOF-PET systems which achieve 225–400 ps CTR. A critical parameter to understand is the optical reflector’s influence on scintillation light collection and transit time variations to the photodetector. To study the effects of the reflector covering the scintillation crystal element on CTR, we have tested the performance of four different reflector materials: Enhanced Specular Reflector (ESR) –coupled with air or optical grease to the scintillator; Teflon tape; BaSO₄ paint alone or mixed with epoxy; and TiO₂ paint. For the experimental set-up, we made use of 3נ3נ10 mm³ fast-LGSO:Ce scintillation crystal elements coupled to an array of silicon photomultipliers (SiPMs) using a novel ‘side-readout’ configuration that has proven to have lower variations in scintillation light collection efficiency and transit time to the photodetector. Results: show CTR values of 102.00.8, 100.21.2, 97.31.8 and 95.01.0 ps full-width-half-maximum (FWHM) with non-calibrated energy resolutions of 10.21.8, 9.91.2, 7.91.2, and 8.61.7% FWHM for the Teflon, ESR (without grease), BaSO₄ (without epoxy) and TiO₂ paint treatments, respectively.

通过包含 511 keV 光子对重合飞行时间 (TOF) 信息，可以提高正电子发射断层扫描 (PET) 重建图像的信噪比 (SNR)。这种 TOF 功能的 SNR 改进程度取决于 PET 系统的重合时间分辨率 (CTR)，这本质上是针对放置在系统中心的点正电子源检测到的所有重合光子对的光子到达时间差的变化。 CTR 由几个因素决定，包括闪烁晶体和光电探测器的固有特性、晶体到光电探测器的耦合配置、反射材料和电子读出配置方案。目前工作的目标是构建一种具有 100 皮秒 (ps) CTR 的新型 TOF-PET 系统，与最先进的 TOF-PET 系统相比，该系统在重建图像 SNR 方面额外提高了 1.5-2.0 倍其 CTR 达到 225–400 ps。需要了解的一个关键参数是光学反射器对闪烁光收集和光电探测器传输时间变化的影响。为了研究覆盖闪烁晶体元件的反射器对 CTR 的影响，我们测试了四种不同反射器材料的性能： 增强型镜面反射器 (ESR) – 与空气或光学油脂耦合到闪烁器；特氟龙胶带； BaSO ₄涂料单独或与环氧树脂混合；和TiO ₂涂料。 对于实验装置，我们使用了 3נ3נ10 mm ³快速 LGSO:Ce 闪烁晶体元件，该元件与硅光电倍增管 (SiPM) 阵列耦合，使用新颖的“侧面读出”配置，已证明该配置具有较低的闪烁变化光收集效率和到达光电探测器的传输时间。结果：显示 CTR 值为 102.00.8、100.21.2、97.31.8 和 95.01.0 ps 全宽半高 (FWHM)，未校准能量分辨率为 10.21.8、9.91.2、7.91.2 Teflon、ESR（不含油脂）、BaSO ₄ （不含环氧树脂）和 TiO ₂涂料处理的半高宽分别为 8.61.7%。