X射线增感屏的图象信息传输特性分析

ANALYSIS OF IMAGE INFORMATION TRANSFER PROPERTIES OF X RAY INTENSIFYING SCREEN

本文采用ＭｏｎｔｅＣａｒｌｏ方法详细模拟了不同能量光子与增感屏的作用过程，对于一种稀土（Ｇｄ２Ｏ２Ｓ∶Ｔｂ）增感屏，计算了出射可见光子数的概率分布、平均出射光子数、统计因子、Ｘ射线检测效率以及ＤＱＥ等增感屏出射可见光子数的概率分布曲线均有三个峰，随着入射Ｘ射线能量的增加，各峰之间距离增大，相对强弱对比增大；其余各曲线在Ｇｄ原子Ｋ壳层结合能（５０２４ｋｅＶ）附近，均有突变这些结果提供了增感屏图象信息传输性能的基本参数。

The interaction process of X rays with intensifying screen has been simulated with the Monte Carlo method in this paper.For a kind of rare earth (Gd 2O 2S∶Tb) intensifying screen,we calculate its light photon probability distribution,average photon number per absorbed X ray, statistical factor,X ray detection efficiency and detective quantum efficiency.There are three peaks in the diagram of light photon probability distribution,and with the increase of incident X ray energy, energy difference and relative intensity of the three peaks enlarge.There are sudden changes at the K edge (50 24keV) of the phosphor material in other diagrams.These results give fundamental parameters of image information transfer properties of X ray intensifying screen,and they can also give guidance for thoroughly studying quantum and noise transfer properties of X ray intensifying screen and X ray imaging system.