利用闪光照相基本原理和成像原理,在直接记录法和转换屏记录法的情况下,研究了闪光照相中影响X射线在材料中光程确定的主要因素.结果表明,影响光程确定的几个因素是:散射效应、光源角分布效应、立体角效应和能谱效应.对于高能闪光照相,散射效应是影响光程确定的最主要因素,散射的存在使光程的测量值比实际值降低20%～40%.因此必须在做CT之前,对散射的影响进行修正.

Primary factors affecting determination of the optical path in radiography are investigated. For two different detect ways, the direct and the converting screen methods, these factors are the same, including the scattering effect, the angle distribution effect of the exposure, and the inverse effect of the exposure to the square of radiographic distance. In the high-energy radiography, the scatter is very serious and it is the most important factor. The scatter effect makes the measured value of optical path 20%～40% lower than its actual value. Before CT reconstruct of the radiographic image, it is necessary to reduce scatter effect from the measured optical path.