Objective. Small-animal positron emission tomography (PET) is a powerful preclinical imaging tool in animal model studies. The spatial resolution and sensitivity of current PET scanners developed for small-animal imaging need to be improved to increase the quantitative accuracy of preclinical animal studies. This study aimed to improve the identification capability of edge scintillator crystals of a PET detector which will enable to apply a crystal array with the same cross-section area as the active area of a photodetector for improving the detection area and thus reducing or eliminating the inter-detector gaps. Approach. PET detectors using crystal arrays with mixed lutetium yttrium orthosilicate (LYSO) and gadolinium aluminum gallium garnet (GAGG) crystals were developed and evaluated. The crystal arrays consisted of 31 × 31 array of 0.49 × 0.49 × 20 mm³ crystals; they were read out by two silicon photomultiplier arrays with pixel sizes of 2 × 2 mm² that were placed at both ends of the crystal arrays. The second or first outermost layer of the LYSO crystals was replaced by GAGG crystals in the two crystal arrays. The two crystal types were identified using a pulse-shape discrimination technique to provide better edge crystal identification. Main results. Using the pulse shape discrimination technique, almost all (except for a few edge) crystals were resolved in the two detectors; high sensitivity was achieved by using the scintillator array and the photodetector with the same areas and achieved high resolution by using crystals with sizes equal to 0.49 × 0.49 × 20 mm³. Energy resolutions of 19.3 ± 1.8% and 18.9 ± 1.5%, depth-of-interaction resolutions of 2.02 ± 0.17 mm and 2.04 ± 0.18 mm, and timing resolutions of 1.6 ± 0.2 ns and 1.5 ± 0.2 ns were achieved by the two detectors, respectively. Significance. In summary, novel three-dimensional high-resolution PET detectors consisting of a mixture of LYSO and GAGG crystals were developed. The detectors significantly improve the detection area with the same photodetectors and thus improve the detection efficiency.

中文翻译：

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使用 LYSO 和 GAGG phoswich 晶体减少高分辨率 PET 检测器的边缘效应

客观的. 小动物正电子发射断层扫描 (PET) 是动物模型研究中强大的临床前成像工具。当前为小型动物成像开发的 PET 扫描仪的空间分辨率和灵敏度需要改进，以提高临床前动物研究的定量准确性。本研究旨在提高 PET 探测器边缘闪烁体晶体的识别能力，使得能够应用与光电探测器有源区具有相同横截面积的晶体阵列来提高探测面积，从而减少或消除干扰-探测器间隙。方法. 开发并评估了使用混合原硅酸镥钇 (LYSO) 和钆铝镓石榴石 (GAGG) 晶体的 PET 探测器。晶体阵列由 0.49 × 0.49 × 20 mm ³晶体的 31 × 31 阵列组成；它们由放置在晶体阵列两端的两个像素大小为 2 × 2 mm ²的硅光电倍增管阵列读取。LYSO 晶体的第二层或第一层最外层被两个晶体阵列中的 GAGG 晶体所取代。这两种晶体类型是使用脉冲形状辨别技术来识别的，以提供更好的边缘晶体识别。主要结果. 使用脉冲形状鉴别技术，几乎所有（除了少数边缘）晶体都在两个探测器中被分辨；^{通过使用具有相同面积的闪烁体阵列和光电探测器实现了高灵敏度，并且通过使用尺寸等于0.49×0.49×20mm 3}的晶体实现了高分辨率。两个探测器实现了 19.3 ± 1.8% 和 18.9 ± 1.5% 的能量分辨率，2.02 ± 0.17 mm 和 2.04 ± 0.18 mm 的相互作用深度分辨率，以及 1.6 ± 0.2 ns 和 1.5 ± 0.2 ns 的时间分辨率，分别。意义. 总之，开发了由 LYSO 和 GAGG 晶体混合物组成的新型三维高分辨率 PET 检测器。该探测器与相同的光电探测器相比，显着提高了探测面积，从而提高了探测效率。