Gratings for multi-resolution edge illumination X-ray phase contrast imaging: concept and simulation.

Edge illumination (EI) is an established X-ray phase-contrast imaging method that relies on gratings to obtain attenuation, differential phase, and dark field contrast. Conventional gratings with one-dimensional line apertures, however, pose a major limitation in geometric flexibility of current EI-setups. That is, the gratings are designed for a fixed magnification and the period and aperture size of the gratings determine the fixed resolution. Changing the magnification can adjust the resolution, since the sample is projected over a smaller or larger detector area, but even a small change in magnification causes a mismatch between beamlets and pixels. To allow multi-resolution EI from a single experimental configuration, a grating which retains the projected period at different magnifications is required. In this paper, a trapezoidal grating that overcomes these limitations is studied using Monte Carlo and ray-tracing simulations, including a flat field experiment, a peak-to-peak contrast-to-noise ratio experiment, and EI scans of test phantoms. This simulation study demonstrates the concept of multi-resolution EI and shows its potential towards a generic and flexible EI setup.