The effect of the rotational orientation of circular photomultipliers in a PET camera block detector design
The effect of the rotational orientation of circular photomultipliers in a PET camera block detector design
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PET 相机块探测器设计中圆形光电倍增管旋转方向的影响
DOI：
10.1109/nssmic.1996.591617
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
S. Yokoyama
中科院分区：
文献类型：
--
作者：
J. Uribe;W. Wong;G. Hu;K. Hicks;Junming Wang;H. Baghaei;Nan Zhang;Hongdi Li;S. Yokoyama
这是一项研究圆形光电倍增管 (PMT) 中几何不对称性对 PET 位置敏感块探测器设计的影响。尽管光电阴极具有旋转对称性，但线焦圆形 PMT 的倍增电极相对于光电阴极的轴不对称。因此，阳极信号存在区域光电阴极差异，这影响位置敏感块探测器的解码特性。在使用 PMT 象限共享配置的块检测器设计 (BGO) 中研究了这种定向效应以及引入光漫射器的效应。研究的 PMT 是 Philips XP-1911（直径 19 mm）。研究了四个解码 PMT 的七个对称和代表性方向，以及一个不对称方向。执行的测量包括块复合脉冲高度谱和晶体解码图。观察到两种方向效应：(A) 解码图中的失真变化，以及 (B) 解码分辨率变化。事实证明，用作光漫射器的圆形塑料件的引入是有用的，可以改善探测器块外围晶体的解码并最大限度地减少解码图的失真。这些测量显示了 PMT 象限共享设计以及传统块设计的最佳 PMT 方向。
This is a study of the effects of geometric asymmetries in circular photomultipliers (PMT) on the design of PET position-sensitive block detectors. The dynodes of linear-focus circular PMTs are asymmetric relative to the axis of the photocathode, despite the rotational symmetry of the photocathode. Hence, there are regional photocathode differences in the anode signal, which affect the decoding characteristics of position sensitive block detectors. This orientation effect, as well as the effect of introducing light diffusers, are studied in a block detector design (BGO) using the PMT-quadrant-sharing configuration. The PMT studied is the Philips XP-1911 (19 mm diameter). Seven symmetrical and representative orientations of the four decoding PMT were investigated, as well as one asymmetric orientation. The measurements performed include block-composite pulse-height spectra and crystal decoding maps. Two orientation effects were observed: (A) distortion variation in decoding maps, and (B) decoding resolution variation. The introduction of circular plastic pieces, used as light diffusers, prove to be useful by improving the decoding of crystals on the periphery of the detector block and minimizing distortion in the decoding map. These measurements have shown optimal PMT orientations for the PMT-quadrant-sharing design, as well as for conventional block designs.