Depth identification accuracy of a three layer phoswich PET detector module
Depth identification accuracy of a three layer phoswich PET detector module
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DOI：
10.1109/23.775567
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发表时间：
1999-06-01
影响因子：
1.8
通讯作者：
Green, MV
中科院分区：
文献类型：
--
作者：
Seidel, J;Vaquero, JJ;Green, MV
我们描述了一个 PET 探测器模块，它提供三个级别的交互深度 (DOI) 信息。该探测器是一个由 2 mm x 2 mm x 12 mm 深的 phoswich 晶体元件组成的 9 x 9 阵列，每个元件由 4 mm 长的 LSO（入口层）、GSO（中间层）和 EGO（出口层）晶体以光学方式端到端连接在一起组成。 EGO 出射层直接耦合到微型位置敏感光电倍增管 (PSPMT)。延迟电荷积分是一种利用这些闪烁体光衰时间差异的方法，用于确定相互作用层。通过沿模块长度扫描 511 keV 狭缝辐射源来测量 DOI 精度，LSO 层为 86%，GSO 层为 80%，EGO 层为 84%。 LSO 在 511 keV 下的能量分辨率为 19%，GSO 为 21%，EGO 为 40%。各层之间的表观增益差异为 2.7:1.9:1.0 (LSO:GSO:BGO)。 LSO 层中的晶体之间的晶体分离良好，GSO 层中的晶体之间的晶体分离可以接受，而 EGO 层中的晶体之间的晶体分离较差，这主要是由于 PSPMT 的明显空间非线性。然而，当 DOI 效应特别显着时，例如，延迟电荷积分方法似乎确实适合获取多级深度信息。用于小动物成像的环径非常小的 PET 扫描仪。
We describe a PET detector module that provides three levels of depth-of-interaction (DOI) information. The detector is a 9 x 9 array of 2 mm x 2 mm x 12 mm deep phoswich crystal elements, each consisting of 4 mm long LSO (entrance layer), GSO (middle layer) and EGO (exit layer) crystals joined optically together end-to-end. The EGO exit layer is directly coupled to a miniature position-sensitive photomultiplier tube (PSPMT). Delayed charge integration, a method that exploits differences in the light decay times of these scintillators, is used to determine the layer-of-interaction. DOI accuracy, measured by scanning a slit source of 511 keV radiation along the length of the module was 86% for the LSO layer, 80% for the GSO layer and 84% for the EGO layer. Energy resolution at 511 keV was 19% for LSO, 21% for GSO and 40% for EGO. Apparent gain differed between layers in the ratios 2.7:1.9:1.0 (LSO:GSO:BGO). Crystal separation was good between crystals in the LSO layer, acceptable between crystals in the GSO layer and poor between crystals in the EGO layer due, primarily, to the pronounced spatial non-linearity of the PSPMT. The delayed charge integration method, however, does appear suitable for obtaining multi-level depth information when DOI effects are particularly significant, e.g. in very small ring diameter PET scanners for small animal imaging.