Wang Hongchang, Berujon Sebastien, Herzen Julia, Atwood Robert, Laundy David, Hipp Alexander, Sawhney Kawal
Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
Institue of Materials Science, Helmholtz-Zentrum Geesthacht, Geesthacht, Germany.
Sci Rep. 2015 Mar 4;5:8762. doi: 10.1038/srep08762.
X-ray imaging techniques that capture variations in the x-ray phase can yield higher contrast images with lower x-ray dose than is possible with conventional absorption radiography. However, the extraction of phase information is often more difficult than the extraction of absorption information and requires a more sophisticated experimental arrangement. We here report a method for three-dimensional (3D) X-ray phase contrast computed tomography (CT) which gives quantitative volumetric information on the real part of the refractive index. The method is based on the recently developed X-ray speckle tracking technique in which the displacement of near field speckle is tracked using a digital image correlation algorithm. In addition to differential phase contrast projection images, the method allows the dark-field images to be simultaneously extracted. After reconstruction, compared to conventional absorption CT images, the 3D phase CT images show greatly enhanced contrast. This new imaging method has advantages compared to other X-ray imaging methods in simplicity of experimental arrangement, speed of measurement and relative insensitivity to beam movements. These features make the technique an attractive candidate for material imaging such as in-vivo imaging of biological systems containing soft tissue.
能够捕捉X射线相位变化的X射线成像技术，与传统吸收式射线照相相比，能够以更低的X射线剂量产生对比度更高的图像。然而，相位信息的提取通常比吸收信息的提取更困难，并且需要更复杂的实验装置。我们在此报告一种用于三维（3D）X射线相衬计算机断层扫描（CT）的方法，该方法可提供关于折射率实部的定量体积信息。该方法基于最近开发的X射线散斑跟踪技术，其中使用数字图像相关算法跟踪近场散斑的位移。除了微分相衬投影图像外，该方法还允许同时提取暗场图像。重建后，与传统吸收式CT图像相比，3D相衬CT图像显示出对比度大大增强。与其他X射线成像方法相比，这种新的成像方法在实验装置的简单性、测量速度以及对光束移动的相对不敏感性方面具有优势。这些特性使该技术成为材料成像的有吸引力的候选方法，例如对包含软组织的生物系统进行体内成像。
