在工业CT系统设计过程中,射线能量选择、探测器结构设计、射线源和探测器匹配等方面都涉及探测器灵敏度问题.研究了影响工业CT光电二极管探测器灵敏度的几个主要因素及其定量关系.首先分析了灵敏度的几个主要影响因素:能量沉积率、绝对闪烁效率、光收集效率、光电转换效率.然后采用蒙特卡罗方法仿真得到闪烁体的能量沉积率、光收集效率,计算了CsI(Tl)闪烁体的荧光转换效率及光电二极管的光电转换效率,定义了闪烁体与光电二极管的匹配度的概念.最后得出具有普遍意义的探测器灵敏度的表达式,理论计算值与实际测量结果最大相差20.4％,实验验证了该灵敏度计算方法的有效性和正确性.%Studying on sensitivity of detector has most guiding significance for the selecting of X-ray Energyt the designing of detector and matching between X-ray source and detector. Several major factors of sensitivity and their quantitative relation were studied. First, factors such as energy deposition rate, absolute scintillation efficiency, light collection efficiency and photoe-lectrical conversion efficiency were analyzed. Then, a simulation for energy deposition rate of scintillation crystal and light collection efficiency was carried out by Monte Carlo method. The fluorescence conversion efficiency of the CsKTl) scintillator and the photoelectric conversion efficiency of the photoelectric diode were computed. The concept of matching between the scintillator and the photoelectric diode was defined. Finally, the sensitivity expression with universal meaning of the detector was obtained. The maximum error between theoretical value and practical measurement result is less than 20. 4%. The experiments show the validity and the accuracy of the computing method of the sensitivity.
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