Localized Phase Retrieval Application for Analyzing Multi-Material Samples

X-ray computed tomography (CT) is a powerful imaging technique that provides three-dimensional insights into the internal structures of objects without mechanical intervention. Initially developed for medical diagnostics, CT has evolved into a versatile tool in various scientific and industrial fields. However, standard absorption-based CT has limitations when imaging materials with low X-ray attenuation or multi-material samples with similar attenuation values, often resulting in insufficient contrast for detailed analysis. To overcome these challenges, phase-contrast CT has emerged as a valuable approach, leveraging changes in the phase of X-rays as they interact with the sample. One of the most accessible phase contrast imaging methods is the propagation-based approach, which typically requires a phase retrieval application. This application increases the contrast of individual structures, but on the other hand, it leads to degradation of the spatial resolution in heterogeneous samples, particularly when high-density particles are present. This paper presents so-called localized phase retrieval, which offers a novel solution to this limitation. Instead of applying the phase retrieval algorithm globally, this method focuses on specific regions within reconstructed tomographic slices, preserving spatial resolution and improving material distinction. This localized approach holds promise for more accurate and efficient analysis of complex multi-material samples, paving the way for advancements in computed tomography applications.