Wunderlich Carolin, Paoletti Riccardo, Guberman Daniel
Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Pisa, 56126 Pisa, Italy.
Dipartimento di Scienze Fisiche, della Terra e dell'Ambiente, Università di Siena, 53100 Siena, Italy.
Sensors (Basel). 2024 Sep 19;24(18):6052. doi: 10.3390/s24186052.
Most single-photon emission computed tomography (SPECT) scanners employ a gamma camera with a large scintillator crystal and 50-100 large photomultiplier tubes (PMTs). In the past, we proposed that the weight, size and cost of a scanner could be reduced by replacing the PMTs with large-area silicon photomultiplier (SiPM) pixels in which commercial SiPMs are summed to reduce the number of readout channels. We studied the feasibility of that solution with a small homemade camera, but the question on how it could be implemented in a large camera remained open. In this work, we try to answer this question by performing Geant4 simulations of a full-body SPECT camera. We studied how the pixel size, shape and noise could affect its energy and spatial resolution. Our results suggest that it would be possible to obtain an intrinsic spatial resolution of a few mm FWHM and an energy resolution at 140 keV close to 10%, even if using pixels more than 20 times larger than standard commercial SiPMs of 6 × 6 mm2. We have also found that if SiPMs are distributed following a honeycomb structure, the spatial resolution is significantly better than if using square pixels distributed in a square grid.
大多数单光子发射计算机断层扫描（SPECT）扫描仪采用带有大尺寸闪烁晶体和50 - 100个大型光电倍增管（PMT）的伽马相机。过去，我们曾提出，通过用大面积硅光电倍增管（SiPM）像素取代PMT，可以降低扫描仪的重量、尺寸和成本，其中将商用SiPM进行求和以减少读出通道的数量。我们用一台小型自制相机研究了该解决方案的可行性，但关于如何在大型相机中实现这一方案的问题仍未解决。在这项工作中，我们通过对一台全身SPECT相机进行Geant4模拟来尝试回答这个问题。我们研究了像素尺寸、形状和噪声如何影响其能量分辨率和空间分辨率。我们的结果表明，即使使用比标准商用6×6 mm² SiPM大20倍以上的像素，也有可能获得几毫米半高宽（FWHM）的固有空间分辨率以及接近10%的140 keV能量分辨率。我们还发现，如果SiPM按照蜂窝结构分布，其空间分辨率明显优于以正方形网格分布的方形像素。
