Numerical Modeling and Experiment for Single Grid-Based Phase-Contrast X-Ray Imaging

Abstract

Conventional x-ray imaging techniques have widely been used for both medical and industrial imaging applications and have in common attenuation-based contrast which arises from differences in elemental composition, thickness, and density of the examined sample. However, they are often limited by low image contrast especially in imaging materials of low atomic number. In this work, we investigated the recently proposed phase-contrast x-ray imaging (PCXI) technique, the so-called single grid-based PCXI, which has great simplicity and minimal requirements on the setup alignment. It allows for imaging of smaller features and variations in the examined sample than conventional attenuation-based x-ray imaging with lower x-ray dose. We performed a systematic simulation using a simulation platform developed by us to investigate the image characteristics. We also performed a preliminary PCXI experiment using an established a table-top setup to demonstrate the performance of the simulation platform. The system consists of an x-ray tube (50 kV p , 5 mAs), a focused-linear grid (200-lines/inch), and a flat-panel detector (48-mm pixel size). According to our results, the simulated contrast of phase images was much enhanced, compared to that of the absorption images. The scattering length scale estimated for a given simulation condition was about 117 nm. It was very similar, at least qualitatively, to the experimental contrast, which demonstrates the performance of the simulation platform. We also found that the level of the phase gradient of oriented structures strongly depended on the orientation of the structure relative to that of linear grids.