Prospects for time-of-flight PET using LSO scintillator
Prospects for time-of-flight PET using LSO scintillator
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DOI：
10.1109/23.775565
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发表时间：
1999-06-01
影响因子：
1.8
通讯作者：
Derenzo, SE
中科院分区：
文献类型：
--
作者：
Moses, WW;Derenzo, SE
我们测量了正硅酸镥（LSO）闪烁体晶体与光电倍增管（PMT）耦合并由511 keV光子激发的定时特性。这些晶体的尺寸适合在PET相机中使用（3x3x30毫米）。在使用两个这样的晶体的探测器之间测量到的符合时间分辨率为475 ps fwhm，明显低于基于小晶体的第一原理预测的300 ps fwhm，并在3毫米立方体中测量。发现这种退化是由闪烁光在闪烁晶体内以准随机角度多次反射引起的，这有两个影响。首先，它降低了晶体内的有效信息传播速度（到有效(n)超过cap=3.9-5.3）。由于入射湮灭光子以n=1的速度传播，来自不同深度相互作用的信息以不同的时间延迟到达PMT。其次，反射角（和路径长度）的随机性引入色散，因此光信号的10%-90%上升时间为1ns。
We present measurements of the timing properties of lutetium orthosilicate (LSO) scintillator crystals coupled to a photomultiplier tube (PMT) and excited by 511 keV photons. These crystals have dimensions suitable for use in PET cameras (3x3x30 mm(3)). Coincidence timing resolution of 475 ps fwhm is measured between detectors utilizing two such crystals, significantly worse than the 300 ps fwhm predicted based on first principles for small crystals and measured in 3 mm cubes. This degradation is found to be caused by the scintillation light undergoing multiple reflections at quasirandom angles within the scintillator crystal, which has two effects. First, it slows down the effective information propagation speed within the crystal (to an effective (n) over cap=3.9-5.3). Since the incident annihilation photon travels with n=1, information from interactions at different depths arrives at the PMT with different time delays. Second, the random nature of the reflection angles (and path lengths) introduce dispersion and so a 10%-90% rise time of 1 ns to the optical signal.