脑专用PET显像探测器自由结构符合与初步实验测试

采用脑PET进行人脑功能的研究对生物医学起到至关重要的作用，为了显著提高脑PET显像质量，增加探测效率、实时显示图像，本文设计一种脑专用PET显像大面积平板型探测系统，该探测系统由两个大面积探头组成，每个大面积探头包含3×3阵列的位置灵敏光电倍增管和多个紧密排布的硅酸钇镥闪烁晶体（Ce：LYSO)阵列。并利用1 μCi的²²Na点源对晶格大小为0.7 mm×0.7 mm等六种LYSO晶体阵列进行晶体性能测试，并选用两块晶格大小为1.5 mm×1.5 mm的LYSO晶体阵列进行一对一符合探测初步断层显像。结果显示，各种晶格大小的LYSO晶体阵列的位置区分轮廓的半高宽平均值在0.38~0.49 mm之间，平均能量分辨率（半高宽）在17.61%~30.40%之间；在对²²Na点源的初步图像断层扫描实验测试中，通过滤波反投影算法获得重建图像的空间分辨率为1.5 mm，验证了大面积平板型探测系统的可行性。

Coincidence of Free Structure and Preliminary Experimental Testing of a Specialized Brain PET Imaging Detector

Brain positron emission tomography (PET) plays an important role in the study of human brain function for biomedical. In order to significantly improve the quality of brain PET imaging, increase detection efficiency, and display images in real time, a specialized large-area panel detection system for brain PET imaging is designed, and preliminary experimental tests are carried out for this design. The PET detection system consists of two large-area probes, each containing a 3×3 array of position-sensitive photomultiplier tubes and multiple tightly arranged array-type Cerium and Yttrium Doped Lutetium Oxyorthosilicate (Ce:LYSO) scintillation crystals. A ²²Na point source with 1 μCi was used to test the crystal properties of LYSO crystal arrays with pixels sized from 0.7 mm×0.7 mm to 2.0 mm×2.0 mm. And two LYSO crystal arrays with pixels of 1.5 mm×1.5 mm were selected for preliminary tomography of one-to-one coincidence detection. The experimental results show that the average FWHMs of position discriminating profiles of LYSO crystal arrays with various pixels are between 0.38 mm and 0.49 mm, and the average values of energy resolution (FWHM) are between 20% and 30%. In the initial image tomography test of ²²Na point source, the resolution of reconstructed image is obtained as 1.5 mm by filtering back projection algorithm, which verifies the feasibility of large-area panel detection system.