高能X光照相CCD成像系统的模糊效应

Analysis and simulation of blurring effect for CCD image system in high-energy radiography

指出了景深、可见光衍射、辐射输运是CCD图像接收系统模糊效应的3个影响因素。用MCNP方法研究了转换屏内的辐射输运,给出了不同入射光子能谱和转换屏厚度下转换屏内能量沉积随半径的变化关系。结果表明:能量沉积随转换屏厚度的增加而线性增加;辐射输运引起的模糊与光子能谱有关,但硬化谱引起的模糊随转换屏厚度的变化小于非硬化谱;转换屏内的辐射输运是CCD图像接收系统模糊效应的主要影响因素;辐射输运引起的模糊和高斯模糊是不同的。

It is pointed out that the depth of focus, diffraction from aperture and radiation scattering are three main sources for image blurring of CCD receiving system. The radiation scattering is studied by MCNP simulation. The distributions of energy deposition in CshT1 crystal under different energy spectrum and depth of screen are given. It is shown that energy deposition increases linearly with the depth of screen increasing. The blurring from radiation scattering is related with the spectrum of photons. Furthermore, the blurring caused by the hardened spectrum changing with the depth of screen is less than that by non-hardened spectrum. It can be seen that the radiation scattering is the main source for image blurring, and the blurring from radiation scattering is different from the Gaussian blurring.