Edge illumination is a phase sensitive X-ray imaging technique, compatible with lab-based X-ray sources. Phase information can be retrieved by displacing two masks relative to each other with the object positioned in between. Phase retrieval then allows the three contrasts, absorption, refraction and dark field, to be individually reconstructed with FBP. In this work, a novel joint reconstruction method is proposed using a combined forward model, allowing the three contrasts to be reconstructed simultaneously, without a retrieval step. This allows for more freedom in the acquisition scheme. The proposed objective function is minimized using a split Barzilai-Borwein gradient method. Improved convergence speed and reconstruction quality on an experimental dataset, compared to existing methods, is shown.
Edge illumination is an emerging X-ray phase contrast imaging technique, which has been successfully transferred from synchrotron facilities to lab-based X-ray systems. Rather than installing a dedicated phase contrast system, our goal is to enable phase contrast imaging in a highly flexible X-ray CT system, FleXCT, a novel scanning system consisting of ten motorized axes. These axes allow movements of not only the sample stage, but also the source and detector. To enable phase contrast imaging, two gratings have to be incorporated in the FleXCT system. In this work, we report on the procedure to determine the optimal grating parameters, relying on numerical simulations. Optimal parameter values are presented for both FleXCT gratings.
Edge illumination X-ray phase contrast imaging is a method which relies on two gratings to obtain attenuation, phase and dark field contrast. Current gratings consist of periodic apertures in a high-absorbing flat plate. While edge illumination was originally designed for parallel-beam imaging, it also works with cone-beam sources when the opening angle is sufficiently low. With higher opening angles, however, current gratings cause a shadow which results in a decreased intensity. In this paper, three alternative grating geometries are studied with Monte-Carlo simulations and their performance is evaluated in terms of shadowing. Results show that the alternative grating geometries significantly reduce shadowing in cone-beam based edge illumination.
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