Truncation Correction for Xray PhaseContrast RegionofInterest Tomography An Xray TalbotLau grating interferometer enables imaging of Xray phase contrast. It can measure material transitions that are difficult to observe with traditional attenuation Xray, for example softtissue variations in medical diagnosis or weakly absorbing materials in optical inspection. Unfortunately, the field of view of a TalbotLau interferometer is limited to few centimeters due to manufacturing constraints of its gratings. For larger objects, this leads to truncation in the projection images. In a tomographic reconstruction, this truncation causes severe artifacts and prevents the reconstruction of quantitatively correct phase coefficients. In this article, we propose a setup and an algorithm that combine in one scan fullfield attenuation with smallfield phase measurements. This allows to extrapolate the phase measurements across the full field, and thereby to greatly alleviate truncation artifacts in the reconstructed volume. Evaluation on simulated and real data shows that the method can reliably reconstruct refraction index decrements, that it outperforms the state of the art, and that its performance is in many cases robust to deviations from the initial assumptions.

A methodical assessment of interpolation techniques to metal artifact reduction in Computed Tomography Metal artifact reduction (MAR) methods are continuously used for minimizing artifacts in Computed Tomography (CTCAT scans) and although they are largely used, there is a lack of suggestions to evaluate such methods (especially the interpolationbased ones). In this paper, we propose an approach for assessment of a MAR method based on interpolation techniques. We have used four interpolation techniques, evaluating their performances in two different scenarios: an artificial image simulation for quantitative assessment, and one real image for qualitative assessment. We have adopted the Sinogram Completion method, widely used for metal artifact reduction. The linear interpolation had presented better results in comparison to other interpolation techniques in both scenarios. The MAR method (Sinogram Completion) associated to the linear interpolation technique presents the most efficient results, which justifies the current researchersu0027 interest in this particular technique.