Westmore M S, Fenster A, Cunningham I A
Imaging Research Laboratories, John P. Robarts Research Institute, London, Ontario, Canada.
Med Phys. 1996 May;23(5):723-33. doi: 10.1118/1.597720.
Low-angle scatter of x rays at diagnostic energies is primarily coherent. This coherence gives rise to interference effects resulting in x-ray diffraction patterns that are characteristic of the scattering material. A method is described of imaging these low-angle (0 degree-10 degrees) x-ray diffraction properties of tissue specimens using a diagnostic x-ray beam and image intensifier-based system. The coherent-scatter cross sections of several materials measured this way are presented. It is shown theoretically that the measurements made with this system can be expressed as the mono-energetic cross section "blurred" by the x-ray spectrum using a linear superposition integral. Experimental results using aluminum powder confirm this. Using a 70 kVp x-ray beam filtered with gadolinium to reduce the spectral width, materials such as water, Lucite, and hydroxyapatite all have significantly different diffraction patterns. The cross sections determined from this analysis from the basis of a unique method of characterizing and identifying tissue samples according to their atomic structure rather than x-ray attenuation properties.
在诊断能量下，X射线的低角度散射主要是相干的。这种相干性会产生干涉效应，从而形成散射材料特有的X射线衍射图案。本文描述了一种利用诊断X射线束和基于图像增强器的系统对组织标本的这些低角度（0度至10度）X射线衍射特性进行成像的方法。给出了通过这种方式测量的几种材料的相干散射截面。从理论上表明，用该系统进行的测量可以用线性叠加积分表示为被X射线谱“模糊”的单能截面。使用铝粉的实验结果证实了这一点。使用用钆过滤以减小光谱宽度的70 kVp X射线束时，水、有机玻璃和羟基磷灰石等材料都有明显不同的衍射图案。根据这种分析确定的截面基于一种根据组织样本的原子结构而非X射线衰减特性来表征和识别组织样本的独特方法。
