Challenges of employing a high-resolution x-ray detector in a coded-aperture x-ray phase-contrast imaging system

In this work, we have evaluated the performance of a coded-aperture (edge-illumination) x-ray phase contrast imaging (CA-XPCi) system employing a high resolution x-ray detector with pixel pitch and size equal to 7.8 µm. Two of the main challenges concerning a high resolution x-ray detector employed in a CA-XPCi system that are fabrication of high resolution x-ray absorption masks and environmental vibration are addressed in this paper. We have investigated both the effect of absorption mask thicknesses and mechanical vibration on the performance of a high resolution CA-XPCi system employing a simulation tool based on a wave-optics model. It is demonstrated how the thickness of absorption mask affects the behavior of the CA-XPCi system when more than 30% of the incident x-ray is transmitted through the absorption masks. The behavior of the CA-XPCi system will change to propagation-based (PB) XPCi one when the transmitted portion of x-rays through absorption masks exceeds 60% of the incident beam. It is also highlighted how mechanical (environmental) vibration has an almost minor effect on CA-XPCi systems with big pixel sizes, however, it has a considerable impact on a CA-XPCi system when a high resolution detector is employed. Albeit a high resolution CA-XPCi system has not been yet realized in reality due to technological bottlenecks related to high resolution mask fabrication, this study provides a comprehensive analysis on the challenges we will face to use a high resolution x-ray detector with the current technology, thus they can be considered in future designs.