Crystal surface and reflector optimization for the SiPM-based dual-ended readout TOF-DOI PET detector
Crystal surface and reflector optimization for the SiPM-based dual-ended readout TOF-DOI PET detector
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DOI：
10.1088/2057-1976/abc45a
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发表时间：
2020-11-01
影响因子：
1.4
通讯作者：
Hong, Seong Jong
中科院分区：
文献类型：
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作者：
Kang, Han Gyu;Yamaya, Taiga;Hong, Seong Jong
硅光电倍增管（SiPM）由于其高增益和低噪声的特性，现在被广泛用于正电子发射断层扫描（PET）的应用。随着飞行时间（TOF）和相互作用深度（DOI）测量技术的进步，PET图像质量得到了改善。对于脑专用PET系统，TOF和DOI信息都有利于提高重建PET图像质量。在以前的研究中，我们提出了基于SiPM的双端读出PET探测器，使用平均时间的方法，以实现符合定时分辨率（CTR）为349 ps和DOI分辨率为2.9 mm。然而，符合定时分辨率（CTR）差于300 ps，因为晶体表面和反射器类型没有优化。本研究旨在研究最佳晶体表面处理和反射器材料，以使用LYSO晶体（2.9 x 2.9 x 20 mm（3））的双端读出PET探测器实现低于200 ps的CTR和低于3 mm的DOI分辨率。采用双端读出法，由两个SiPM读出LYSO晶体内部的闪烁光。CTR和DOI分辨率是用两种不同的晶体表面（抛光和锯切）和三种不同的ESR反射器材料方案（即，空气耦合），ESR与光学油脂和聚四氟乙烯。我们分别使用V775 N TDC模块（35 ps bit（-1））和V965 QDC模块对定时和能量信号进行数字化。锯切LYSO晶体和ESR与空气耦合的组合导致最好的CTR（188 - 32 ps）和DOI分辨率（2.9 - 0.2 mm）与双端读出配置。我们得出结论，双端读出方法结合锯切晶体和ESR反射器与空气耦合可以提供亚200 ps的CTR和亚3.0 mm DOI分辨率同时。
Silicon photomultipliers (SiPMs) are now widely used for positron emission tomography (PET) applications because of their high gain and low noise characteristics. The PET image quality has been improved with the advancement of time-of-flight (TOF) and depth-of-interaction (DOI) measurement techniques. For brain-dedicated PET systems, both TOF and DOI information are beneficial for enhancing the reconstructed PET image quality. In a previous study, we proposed SiPM-based dual-ended readout PET detectors that used a mean time method to achieve coincidence timing resolution (CTR) of 349 ps and DOI resolution of 2.9 mm. However, the coincidence timing resolution (CTR) was worse than 300 ps since the crystal surface and the reflector type were not optimized. This study aimed at investigating the optimal crystal surface treatment and the reflector material to achieve a sub-200 ps CTR and sub-3 mm DOI resolution with a dual-ended readout PET detector using an LYSO crystal (2.9 x 2.9 x 20 mm(3)). The scintillation light inside the LYSO crystal was read out by two SiPMs using the dual-ended readout method. The CTR and DOI resolution were measured with two different crystal surfaces (polished and saw-cut) and three different reflector material scenarios of ESR without grease (i.e., air coupling), ESR with optical grease and Teflon. We digitized the timing and energy signals by using a V775N TDC module (35 ps bit(-1)) and V965 QDC module, respectively. The combination of the saw-cut LYSO crystal and the ESR with air coupling resulted in the best CTR (188 32 ps) and DOI resolution (2.9 0.2 mm) with the dual-ended readout configuration. We concluded the dual-ended readout method in combination with the saw-cut crystal and the ESR reflector with air coupling can provide a sub-200 ps CTR and sub-3.0 mm DOI resolution simultaneously.