Du Huini, Yang Yongfeng, Glodo Jarek, Wu Yibao, Shah Kanai, Cherry Simon R
Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA.
Phys Med Biol. 2009 Mar 21;54(6):1757-71. doi: 10.1088/0031-9155/54/6/023. Epub 2009 Mar 3.
We investigate a novel detector using a lutetium oxyorthosilicate (LSO) scintillator and YGG (yttrium-aluminum-gallium oxide:cerium, Y(3)(Al,Ga)(5)O(12):Ce) phosphor to construct a detector with continuous depth-of-interaction (DOI) information. The far end of the LSO scintillator is coated with a thin layer of YGG phosphor powder which absorbs some fraction of the LSO scintillation light and emits wavelength-shifted photons with a characteristic decay time of approximately 50 ns. The near end of the LSO scintillator is directly coupled to a photodetector. The photodetector detects a mixture of the LSO light and the light emitted by YGG. With appropriate placement of the coating, the ratio of the light converted from the YGG coating with respect to the unconverted LSO light can be made to depend on the interaction depth. DOI information can then be estimated by inspecting the overall light pulse decay time. Experiments were conducted to optimize the coating method. 19 ns decay time differences across the length of the detector were achieved experimentally when reading out a 1.5 x 1.5 x 20 mm(3) LSO crystal with unpolished surfaces and half-coated with YGG phosphor. The same coating scheme was applied to a 4 x 4 LSO array. Pulse shape discrimination (PSD) methods were studied to extract DOI information from the pulse shape changes. The DOI full-width-half-maximum (FWHM) resolution was found to be approximately 8 mm for this 2 cm thick array.
我们研究了一种新型探测器，它使用正硅酸镥（LSO）闪烁体和钇铝镓氧化物（YGG：铈，Y(3)(Al,Ga)(5)O(12):Ce）磷光体来构建一个具有连续相互作用深度（DOI）信息的探测器。LSO闪烁体的远端涂有一层薄薄的YGG磷光体粉末，该粉末吸收一部分LSO闪烁光，并发射具有约50 ns特征衰减时间的波长移位光子。LSO闪烁体的近端直接与光电探测器耦合。光电探测器检测LSO光和YGG发射的光的混合光。通过适当放置涂层，可以使从YGG涂层转换的光相对于未转换的LSO光的比例取决于相互作用深度。然后可以通过检查整体光脉冲衰减时间来估计DOI信息。进行了实验以优化涂层方法。当读出一个1.5×1.5×20 mm(3)、表面未抛光且一半涂有YGG磷光体的LSO晶体时，通过实验实现了探测器长度上19 ns的衰减时间差异。相同的涂层方案应用于一个4×4的LSO阵列。研究了脉冲形状甄别（PSD）方法，以从脉冲形状变化中提取DOI信息。对于这个2厘米厚的阵列，发现DOI半高宽（FWHM）分辨率约为8毫米。
