Demonstration of phase-contrast X-ray computed tomography using an X-ray interferometer

Abstract

Phase-contrast X-ray computed tomography (PCX-CT) using an X-ray interferometer is introduced for observing a density distribution inside an organic material. PCX-CT images are compared with an absorption-contrast X-ray CT image and shown to be highly sensitive. To convert an interference pattern into an image of phase-shift distribution, which is put into a CT algorithm, the author applied subfringe analysis techniques, such as the Fourier-transform method and the fringe scanning method. In the case presented here, a plastic sphere is used as a test sample, and the resulting spatial resolution of the PCX-CT image is less than 40 μm. The signal-to-noise ratio (S/N) for the PCX-CT image is increased to ten times that for an absorption-contrast CT image. The S/N can be further increased by suppressing the movement of the interference pattern caused by air flow around the interferometer.