X射线散射对面密度测量结果影响的数值模拟研究

定性分析了X射线散射对面密度测量结果的影响,给出了面密度测量结果偏差的评估表达式。利用蒙特卡罗方法数值模拟了不同照相布局、不同光源能量和不同材料类型情形下X射线散射对测量结果的影响。模拟结果表明:在无防护窗情形下,被测物自身散射将导致测量结果偏小;在有防护窗情形下,前窗散射对测量结果的影响不大,后窗散射对测量结果的影响与接收介质离被测物的距离有关,具体表现为距离越小影响越大;在一定光子能量范围内,光源能量越低散射导致的测量偏差越大;被测物的原子序数和密度越大,散射导致的测量偏差越大。

Numerical simulation study of effects of X-ray scattering on areal density measurement results

The effects of X-ray scattering on areal density measurement results and an expression of measurement results deviation are obtained with a qualitative analysis. The effects at different photographic layout, energy sources and material types are studied using Monte-Carlo method. The simulation results show that without protective windows, the scattering from the object would reduce the measurement results; with protective windows, the front window scattering has little effects on the measurement results, and the effects of back window scattering are related to the sample-scintillator distance, the shorter the distance is, the greater the effects are; in a certain energy range, the lower the energy of photon is, the larger the measurement result error is; the bigger the atomic number and density of the object are, the larger the measurement result error is.