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小动物正电子发射断层扫描成像(Positron Emission Tomography,PET)是临床前生物医学研究的重要工具,但小动物PET要同时达到高空间分辨率和高效率必须使用三维深度测量探测器。本工作使用位置灵敏雪崩光二极管(Position-Sensitive Avalanche Photodiode,PSAPD)和位置灵敏硅光电倍增管(Position-Sensitive Silicon Photomultipliers,PS-Si PM)双端读出,测量了晶体大小为0.7~0.44 mm的高分辨率硅酸镥晶体阵列,其中对一种最新研发成功的PS-Si PM进行了首次测试。首先对PS-Si PM和PSAPD的信噪比进行了测量,然后对使用PS-Si PM和PSAPD的双端读出探测器模块的晶格分辨图、能量分辨率和相互作用深度分辨率分别进行了测量。实验发现,PSAPD的信噪比远远优于PS-Si PM,使用PSAPD的探测器可以分辨0.44 mm的晶格阵列和最好达到1.4 mm的深度分辨率,而使用PS-Si PM的探测器模块可以分辨0.7 mm的硅酸镥晶体阵列和达到2.9 mm的深度分辨率。从得到的晶格分辨图、能量分辨率和相互作用深度分辨率上来看,使用PSAPD的探测器模块要优于使用PS-Si PM的探测器。这需要提高PS-Si PM的信噪比来进一步提高探测器分辨更小截面晶格的能力,提高PS-Si PM微单元的数量来降低饱和效应从而提高探测器的相互作用深度分辨率。从实验结果可以看出,基于PSAPD的三维相互作用深度测量PET探测器具有更好的性能,今后计划使用新的PS-Si PMs和Si PM阵列进行该类型探测器的研发。
Positron Emission Tomography (PET) is an important tool in preclinical biomedical research. However, small animal PET must use three-dimensional depth measurement probes to achieve high spatial resolution and high efficiency. In this work, a readout was performed at both ends using a Position-Sensitive Avalanche Photodiode (PSAPD) and a Position-Sensitive Silicon Photomultiplier (PS-Si PM). The crystal size was measured from 0.7 to 0.44 mm Resolution high-resolution Li silicate crystal array with the first test of a newly developed PS-Si PM. First, the signal-to-noise ratio of PS-Si PM and PSAPD was measured, and then the lattice resolution, energy resolution and interaction depth resolution of the double-ended readout detector module using PS-Si PM and PSAPD were respectively The measurement. It has been found experimentally that the signal to noise ratio of PSAPD is much better than that of PS-Si PM. Detectors using PSAPD can resolve a 0.44 mm lattice array and optimally achieve a depth resolution of 1.4 mm. Detectors using PS-Si PM The module is capable of resolving a 0.7 mm x-ray crystal array and reaching a depth resolution of 2.9 mm. From the obtained lattice resolution, energy resolution and interaction depth resolution, the detector module using PSAPD is superior to the detector using PS-Si PM. This requires increasing the signal-to-noise ratio of the PS-Si PM to further increase the detector’s ability to resolve smaller cross-section lattices, increasing the number of PS-Si PM microcells to reduce saturation effects, and increasing the depth resolution of the detector interaction. From the experimental results, it can be seen that PET detector based on PSAPD has better performance and it is planned to use this new PS-Si PMs and Si PM array to develop this type of detector.