Center for Advanced Material Diagnostic Technology, Shenzhen Technology University, Shenzhen 518118, People's Republic of China. Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, People's Republic of China.
Phys Med Biol. 2021 Mar 12;66(6):065023. doi: 10.1088/1361-6560/abe761.
Both monolithic and semi-monolithic scintillator positron emission tomography (PET) detectors can measure the depth of interaction with single-ended readout. Usually scintillators with a thickness of 10 mm or less are used since the position resolutions of the detectors degrade as the scintillator thickness increases. In this work, the performance of a 20 mm thick long rectangular semi-monolithic scintillator PET detector was measured by using both single-ended and dual-ended readouts with silicon photomultiplier (SiPM) arrays to provide a high detection efficiency. The semi-monolithic scintillator detector consists of nine lutetium-yttrium oxyorthosilicate slices measuring 1.37 × 51.2 × 20 mm with erythrocyte sedimentation rate foils of 0.065 mm thickness in between the slices. The SiPM array at each end of the scintillator detector consists of 16 × 4 SiPMs with a pixel size of 3.0 × 3.0 mm and a pitch of 3.2 mm. The 64 signals of each SiPM array are processed by using the TOFPET2 application-specific integrated circuit individually. All but the edge slices can be clearly resolved for the detectors with both single-ended and dual-ended readouts. The single-ended readout detector provides an average full width at half maximum (FWHM) Y (continuous direction) position resolution of 2.43 mm, Z (depth direction) position resolution of 4.77 mm, energy resolution of 25.7% and timing resolution of 779 ps. The dual-ended readout detector significantly improves the Y and Z position resolutions, slightly improves the energy and timing resolution at the cost of two photodetectors required for one detector module and provides an average FWHM Y position resolution of 1.97 mm, Z position resolution of 2.60 mm, energy resolution of 21.7% and timing resolution of 718 ps. The energy and timing resolution of the semi-monolithic scintillator detector in this work are worse than those of the segmented scintillator array detector and need to be further improved. The semi-monolithic scintillator detector described in this work reduces costs as compared to the traditional segmented scintillator array detector and reduces the edge effect as compared to the monolithic scintillator detector.
单晶和半单晶闪烁体正电子发射断层扫描（PET）探测器都可以使用单端读出测量相互作用深度。由于探测器的位置分辨率随闪烁体厚度的增加而降低，因此通常使用厚度为 10mm 或更薄的闪烁体。在这项工作中，使用硅光电倍增管（SiPM）阵列的单端和双端读出测量了 20mm 厚的长矩形半单晶闪烁体 PET 探测器的性能，以提供高检测效率。半单晶闪烁体探测器由九块硅酸镥钇（LuYSO）闪烁体切片组成，每个切片尺寸为 1.37×51.2×20mm，切片之间夹有 0.065mm 厚的红细胞沉降率箔。每个闪烁体探测器两端的 SiPM 阵列由 16×4 个 SiPM 组成，每个 SiPM 的像素尺寸为 3.0×3.0mm，间距为 3.2mm。每个 SiPM 阵列的 64 个信号分别由 TOFPET2 专用集成电路处理。对于使用单端和双端读出的探测器，除了边缘切片外，所有切片都可以清晰地分辨出来。单端读出探测器提供的平均全宽半最大值（FWHM）Y（连续方向）位置分辨率为 2.43mm，Z（深度方向）位置分辨率为 4.77mm，能量分辨率为 25.7%，时间分辨率为 779ps。双端读出探测器显著提高了 Y 和 Z 位置分辨率，在牺牲一个探测器模块所需的两个光电探测器的情况下，略微提高了能量和时间分辨率，提供的平均 FWHM Y 位置分辨率为 1.97mm，Z 位置分辨率为 2.60mm，能量分辨率为 21.7%，时间分辨率为 718ps。与分段闪烁体阵列探测器相比，本工作中的半单晶闪烁体探测器的能量和时间分辨率较差，需要进一步改进。与传统的分段闪烁体阵列探测器相比，本工作中描述的半单晶闪烁体探测器降低了成本，与单晶闪烁体探测器相比，降低了边缘效应。
