Towards a dual phase grating interferometer on clinical hardware

In the last decades, several interferometric phase sensitive X-ray imaging setups with highly incoherent sources were developed. One of the clinically most promising setups is the Talbot-Lau interferometer. However, these systems still suffer from some challenges that prevent their clinical use. One challenge is the post-patient attenuation of the analyzer grating, that doubles the effective dose. To address this issue, new setup designs were proposed using a second phase grating, instead of the absorbing analyzer grating. Those two phase gratings together can create a beat pattern at the detector that can be resolved by the detector directly. In this paper the simulation tool CXI is validated for dual phase grating setups. Using the simulation, we found an optimal setup using existing gratings. A first feasibility study is shown with two phase gratings of 4.12 and 4.37 μm. The computed visibility of 4.6 % in simulation is in good accordance with the experimental visibility of 4 %. The final visibility is a trade-off between the inter-grating distance, grating-detector distance, the beat period and the point spread function of the detector.