Theoretical Consideration on Refraction-contrast CT Based on the Superimposed Wavefront Imaging of Diffraction-enhanced X-rays

Abstract

Phase-contrast CT using high-brilliance synchrotron radiation X-rays has been used to visualize microanatomical structures in various biological specimens because it can image biological soft tissues with high contrast. However, the imaging methods proposed so far for phase-contrast CT require a certain space between the subject and the X-ray camera, which makes it difficult to obtain high spatial resolution because blurring due to penumbra caused by the distance between the subject and the X-ray camera cannot be reduced. To resolve this problem, we have developed an X-ray diffraction wavefront imaging technique called Superimposed wavefront imaging of diffraction-enhanced X-rays (SWIDeX) that uses a Laue-case Si angle analyzer, which is tightly attached to a scintillator that converts X-rays to visible light, to obtain second-order differential phase contrast images. This method minimizes the space between the subject and the X-ray camera and provides higher spatial resolution than conventional methods. In this paper, we derive a CT reconstruction theorem using SWIDeX and demonstrate the effectiveness of the proposed method from actual imaging experiments using synchrotron radiation.