基于沿单层LYSO晶体阵列深度多层反射膜分布的深度编码PET探测器研究

本文提出了在单层LYSO晶体阵列中，采用沿晶体深度布局多层反射膜，并通过SiPM阵列单端读出，从而进行深度测量的PET探测器方法。制作了2个晶体大小为3 mm×3 mm×20 mm的2×2 LYSO晶体阵列，分别布局2层和4层反射膜，对该探测器性能的实验测量结果表明，此探测器可清楚区分所有晶体单元。对于布局2层反射膜的探测器，上下两层事件平均正确指定的概率为85.1%，4个不同深度事件的平均正确指定概率为65.5%；对于布局4层反射膜的探测器，4个不同深度事件的平均正确指定概率为74.8%。布局4层反射膜的探测器的深度分辨率优于布局2层反射膜的探测器。两个探测器的平均能量分辨率分别为18.0%和12.2%。这种可分辨γ射线与晶体作用点深度的新型PET探测器，可用于今后研发高性能脑专用、全身和全景PET成像系统。

Depth Encoding PET Detector Using Two and Four Reflector Arrangements along Depth of Single Layer LYSO Array

In this paper, the depth encoding PET detector using different reflector arrangements along the depth of single layer LYSO crystal arrays with SiPM array single-ended readout was proposed. 2×2 LYSO arrays with crystal size of 3 mm×3 mm×20 mm using four and two reflector arrangements along the crystal depth were fabricated and measured. The experimental results show that all crystals can be clearly resolved from the measured flood histograms. For the detector with two reflector arrangements, the average probabilities to make correct assignment to each half and quarter of the crystals are 85.1% and 65.5%, respectively. For the detector with four reflector arrangements, the average probability to make correct assignment to each quarter of the crystals is 74.8%. The depth of interaction (DOI) resolution of the detector with four reflector arrangements is better than that of the detector with two reflector arrangements. The average energy resolutions of the two detectors are 18.0% and 12.2%. The depth encoding PET detector proposed in this paper achieves good DOI resolution with single-ended readout. The detector can be used to develop high performance dedicated brain, whole-body and total-body PET scanners in the future.