Westmore M S, Fenster A, Cunningham I A
Imaging Research Laboratories, John P. Robarts Research Institute, London, Ontario, Canada.
Med Phys. 1997 Jan;24(1):3-10. doi: 10.1118/1.597917.
A new special-purpose computed tomographic (CT) imaging system is described which produces images based on measurements of the low-angle (0-10 degrees) x-ray diffraction properties of an object. Low-angle scatter in the diagnostic x-ray energy range is dominated by coherent scatter, and the system uses first-generation CT geometry to acquire a diffraction pattern for each pencil beam. The patterns are used to reconstruct a series of images which represent the coherent-scatter intensity at a series of scatter angles. To demonstrate the potential of coherent-scatter CT (CSCT), the scanner has been built and used to image a phantom consisting of a water-filled Lucite cylinder containing rods of polyethylene, Lucite, polycarbonate, and nylon. In this paper, the system is described and a sequence of CSCT images of this phantom is shown. Coherent-scatter cross sections of these materials are generated for each pixel from this sequence of images and compared with cross sections measured separately. The resulting excellent agreement shows that the angular-dependent coherent-scatter cross section can be accurately imaged in a tomographic slice through an object. These cross sections give material-specific information about the object. The long-term goal of this research is to make measurements of bone-mineral content for every pixel in a tomographic slice.
描述了一种新型专用计算机断层扫描（CT）成像系统，该系统基于对物体低角度（0 - 10度）X射线衍射特性的测量来生成图像。在诊断X射线能量范围内，低角度散射主要由相干散射主导，并且该系统使用第一代CT几何结构为每个笔形束获取衍射图案。这些图案用于重建一系列图像，这些图像代表了一系列散射角度下的相干散射强度。为了证明相干散射CT（CSCT）的潜力，已构建了该扫描仪并用于对一个体模进行成像，该体模由一个装有聚乙烯、有机玻璃、聚碳酸酯和尼龙棒的充水有机玻璃圆柱体组成。本文描述了该系统，并展示了这个体模的一系列CSCT图像。从这一系列图像中为每个像素生成这些材料的相干散射截面，并与单独测量的截面进行比较。结果显示出的极佳一致性表明，通过物体的断层切片可以准确地对角度相关的相干散射截面进行成像。这些截面给出了关于物体的特定材料信息。这项研究的长期目标是对断层切片中的每个像素进行骨矿物质含量测量。
