光栅成像的锥束相位CT重建算法

X射线相位衬度成像对弱吸收物质有着独有的高密度分辨率,在医学、生物学、材料学等领域显示出良好的应用前景.但是其中的干涉成像法、衍射增强成像法和同轴成像法具有一定局限性,难以被广泛应用.光栅成像克服了以往相位衬度成像的缺陷,也使相位衬度成像向锥束成像发展成为可能.本文致力于锥束相位X射线计算机断层摄影术(CT)重建算法的研究,根据基于光栅的锥束相位成像的特点,利用吸收CT中FDK (Feldkamp-Davis-Kress)重建算法的思想,发展出适用于锥束相位成像的CT重建方法.该方法为滤波反投影类型,以相位一阶导数像为投影值,直接重建物体的相位项.通过仿真验证了算法的正确性.

Reconstruction Algorithm of Cone-Beam Phase X-Ray Computer-Tomography Based on Grating Imaging

X-ray phase contrast imaging always provides high density resolution for weakly absorbing material, and shows wide prospect of application in many fields such as medicine, biology and material science. However, due to the limitation of interferometic imaging method, diffraction enhanced imaging method and in-line imaging method, these methods need either highly coherent or highly monochromatic X-ray, and cannot provide a large field of view, none of them is very widely used. Grating imaging overcomes the limitations of above imaging methods and enables phase contrast imaging to develop into the form of cone-beam imaging. The research of the reconstruction algorithm of cone-beam phase X-ray computer tomography (CT) is studied, based on the characteristic of cone-beam grating imaging and the theory of Feldkamp-Davis-Kress (FDK) reconstruction algorithm. This method belongs to filtered back-projection and can reconstruct the phase item of object directly with the derivative of the phase term as projection, and the algorithm is proved by simulated results.