当入射到积分模式辐射探测器上的每一入射粒子最终产生的可检测光电子数服从参数为g的泊松分布时，探测器的量子探测效率极限值的计算式为 g/（ g＋1）。该工作给出了此计算式在某种程度上更易理解的另一推导，并计算了典型透镜耦合医用X射线数字成像探测器的量子探测效率。计算表明，在光圈数为1．0，系统放大率为11．5倍，采用白色衬底碘化铯闪烁体屏这样的典型情况下，因低的透镜耦合效率造成的量子探测效率的降低仅为33％，在实际应用中尚可接受。%When the number of photoelectrons caused by every incident ionizing radiation particle obeys Poisson distribution with parameter g , the theoretical limitation of the detective quantum efficiency ( DQE) for integra-tion mode radiation detector is g/( g+1) .A new method for deducing this formula will be given in this work , then calculate the DQE of typical lens coupled clinical digital radiography detector .Calculation indicates that in typical system with F -number 1.0, magnification 11.5, white substrate CsI scintillator screen , the decrease of DQE due to low lens couple efficiency is only 33%, which is still acceptable in applications .
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