该文选用了一种现有的大动物单光子发射断层成像(single photon emission computed tomography, SPECT)探测器架构, 在此基础上对其中的准直器系统进行了参数设计。通过理论计算视野(field of view, FOV)中心点的空间分辨率和探测效率以及投影交叠比例并设置一定约束条件, 选出了6组设计方案作为评估对象, 并利用了一种性能评估方法, 通过计算选定像素的局部脉冲响应的对比度恢复系数(contrast recovery coefficient, CRC)和方差, 对6组不同准直器设计方案进行了评估, 给出了最优化的设计方案, 并通过热圆柱模型的数值模拟成像实验对该设计方案进行了成像效果验证。理论计算和数值模拟结果表明：该设计方案在满足视野中心探测效率不低于0.03%的情况下, 热圆柱成像空间分辨率不低于3.0 mm, 达到了技术指标要求。
This study analyzed the collimator parameters of a large animal single photon emission computed tomography (SPECT) detector. Six collimator design schemes were chosen by thoretical calculation of the spatial resolution, the sensitivity at the field of view (FOV) center and the projection overlap ratio with specified constraints. A performance evaluation method was used to evaluate the six collimator design schemes by calculating the contrast recovery coefficient (CRC) and the variance of the local impulse response of selected pixels to find the best design scheme. The imaging effect of the design scheme was verified by numerical simulations of imaging experiments of a hotrod phantom. The theoretical calculations and the numerical simulations demonstrate that the design scheme gives a spatial resolution of the hotrod phantom that is better than 3.0 mm with better than 0.03% sensitivity at the FOV center, which meets the technical requirements.
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