Multimodal single-shot x-ray phase-contrast imaging using a high-resolution micropillar-based grating

Abstract

Grating-based X-ray phase-contrast imaging (XPCi) systems offer higher sensitivity compared to other XPCi methods; however, realizing a high-resolution, compact, dose-efficient imaging system has been a significant challenge from technological and practical points of view until now. X-ray gratings quality and characteristics directly determine the final imaging quality, where a proper grating fabrication process can potentially minimize image artifacts and increase the system visibility. To achieve a high-resolution, compact, dose-efficient XPCi system, high-resolution detectors and high-resolution X-ray absorption gratings are a must. Moreover, an efficient image processing method is required to retrieve multimodal XPCi information—transmission, refraction (phase-contrast), and dark-field—efficiently and simultaneously. In this work, we report on a compact XPCi system that enables multimodal information retrieval through single-shot imaging with two-directional sensitivity. We first present an elegant cost-effective fabrication method to make high-resolution micropillar-based X-ray absorption gratings. A prototype 2D grating is fabricated with micropillars with 4 μm in diameter, periodicity of 16.3 μm, and aspect ratio of more than 40. This grating is then employed along with a prototype hybrid a-Se/CMOS direct conversion high-resolution X-ray detector with a pixel pitch of 8 μm in a compact system with a polychromatic microfocus source to perform X-ray phase-contrast imaging of various samples. We successfully demonstrate a single-shot XPCi and retrieve multimodal XPCi data with transmission and dark-field metrics. The final system is a promising candidate for XPCi applications as it facilitates single-shot imaging, which reduces the exposure dose on samples and yields multimodal XPCi images efficiently, all in a compact bench-top setup. The delivered X-ray dose at the sample, resolution of the system, and compactness of the reported imaging setup are potentially beneficial for ex vivo, in vivo, and computed tomography (CT) imaging applications.