Matsumoto Takahiro, Yamaya Taiga, Yoshida Eiji, Nishikido Fumihiko, Inadama Naoko, Murayama Hideo, Suga Mikio
Chiba University, 1-33 Yayoicho, Inage-ku, Chiba, 263-8522, Japan,
Radiol Phys Technol. 2014 Jan;7(1):43-50. doi: 10.1007/s12194-013-0229-y. Epub 2013 Aug 9.
We are developing a novel PET detector with 3D isotropic resolution called a crystal (X'tal) cube. The X'tal cube detector consists of a crystal block all 6 surfaces of which are covered with silicon photomultipliers (SiPMs). We have developed a prototype detector with 3D isotropic 1 mm resolution. On the other hand, when the X'tal cubes are arranged to form a PET scanner, insensitive inter-detector gaps made by the SiPM arrays should not be too wide, or, better yet, they should be removed. Reduction of the number of SiPMs will also be reflected in the production costs. Therefore, reducing the number of faces to be connected to the SiPMs has become our top priority. In this study, we evaluated the effect of reducing the number of SiPMs on the positioning accuracy through numerical simulations. Simulations were performed with the X'tal cube, which was composed of a 6 × 6 × 6 array of Lu2x Gd2(1-x)SiO5:Ce crystal elements with dimensions of (3.0 mm)(3). Each surface of the crystal block was covered with a 4 × 4 array of SiPMs, each of which had a (3.0 mm)(2) active area. For material between crystal elements, we compared two: optical glue and an air gap. The air gap showed a better crystal identification performance than did the optical glue, although a good crystal identification performance was obtained even with optical glue for the 6-face photodetection. In conclusion, the number of photodetection faces could be reduced to two when the gap material was air.
我们正在开发一种名为晶体（X'tal）立方体的具有三维各向同性分辨率的新型正电子发射断层显像（PET）探测器。X'tal立方体探测器由一个晶体块组成，其所有6个表面均覆盖有硅光电倍增管（SiPM）。我们已经开发出了一种具有三维各向同性1毫米分辨率的原型探测器。另一方面，当将X'tal立方体排列形成PET扫描仪时，由SiPM阵列产生的探测器间不灵敏间隙不应过宽，或者更好的是，应将其消除。SiPM数量的减少也会反映在生产成本上。因此，减少与SiPM连接的面的数量已成为我们的首要任务。在本研究中，我们通过数值模拟评估了减少SiPM数量对定位精度的影响。使用由6×6×6阵列的Lu2x Gd2(1 - x)SiO5:Ce晶体元件组成、尺寸为(3.0毫米)³的X'tal立方体进行模拟。晶体块的每个表面都覆盖有一个4×4阵列的SiPM，每个SiPM的有效面积为(3.0毫米)²。对于晶体元件之间的材料，我们比较了两种：光学胶水和气隙。气隙显示出比光学胶水更好的晶体识别性能，尽管对于六面光电探测，即使使用光学胶水也能获得良好的晶体识别性能。总之，当间隙材料为空气时，光电探测面的数量可以减少到两个。
