X-ray computed tomography reconstruction algorithm for refractive index gradient

Abstract: The aim of this research is to reconstruct the 3D X-ray refractive index gradient maps by the proposed vector Radon transform and its inverse, assuming that the small-angle deviation condition is met. Theoretical analyses show that the X-ray beam can be modeled as a streamline with continuous change of direction in a row when measured in one grating period, which allows the extraction of the refraction angle signals. Experimental results show that all the 2D refraction signals of different directions can be acquired by a standard circular scanning procedure, which is typically used in the X-ray differential phase-contrast computed tomography. Furthermore, the 3D refractive index gradient maps that contain the directional density changes, can also be accurately reconstructed.