Effect of finite phosphor thickness on detective quantum efficiency.
Effect of finite phosphor thickness on detective quantum efficiency.
复制标题
有限磷光体厚度对探测量子效率的影响。
DOI：
10.1118/1.596335
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发表时间：
1989
期刊：
影响因子：
3.8
通讯作者：
R. Holmes
中科院分区：
文献类型：
--
作者：
R. Nishikawa;M. Yaffe;R. Holmes
在本文中，我们从理论上描述了荧光屏的有限厚度与其空间频率相关的探测量子效率 DQE(f-) 之间的关系。屏幕的有限厚度导致在给定的 X 射线相互作用的爆发中从屏幕发射的光量子总数以及光爆发内量子的空间分布（即光爆发的形状或点扩散函数（PSF））的变化。爆发幅度的变化导致 DQE 与空间频率无关的降低，其特征在于闪烁效率 As。随着空间频率的增加，PSF 的变化导致 DQE 滚降，我们用函数 Rc(f) 来表征这一点。 As 和 Rc(f) 都可以根据荧光体发射的光突发的空间傅立叶光谱分布的矩来确定，因此它们是相关的： As 是 Rc(f) 的比例因子。我们的理论预测，输出端出现的所有光突发必须具有相同的幅度才能最大化 As，并且必须具有相同的形状才能最大化 Rc(f)。这些要求可能导致这样的结果：即使在高空间频率下，具有最高调制传递函数的荧光屏也不一定具有最高的DQE(f)。
In this paper we describe theoretically the relationship between the finite thickness of a phosphor screen and its spatial-frequency-dependent detective quantum efficiency DQE(f-). The finite thickness of the screen causes a variation in both the total number of light quanta emitted from the screen in a burst from a given x-ray interaction and in the spatial distribution of the quanta within the light burst [i.e., shape or point spread function (PSF) of the light burst]. The variation in magnitude of the burst gives rise to a spatial-frequency-independent reduction in DQE, characterized by the scintillation efficiency As. The variation in PSF causes a roll off in DQE with increasing spatial frequency which we have characterized by the function Rc(f). Both As and Rc(f) can be determined from the moments of the distribution of the spatial Fourier spectrum of light bursts emitted from the phosphor and thus they are related: As is a scaling factor for Rc(f). Our theory predicts that it is necessary for all light bursts which appear at the output to have the same magnitude to maximize As and the same shape to maximize Rc(f). These requirements can lead to the result that the fluorescent screen with the highest modulation transfer function will not necessarily have the highest DQE(f) even at high spatial frequencies.