Optimización del método de Paganin para la recuperación de fase en imágenes de contraste de rayos X

Abstract

This work addresses the optimization of the Paganin method for phase retrieval in X-ray phase contrast imaging. The article focuses on analyzing the applicability and effectiveness of various mathematical approaches and experimental techniques with images simulated in Geant4 and others taken in the laboratory. To this end, the original Paganin algorithm is modified, including a higher-order approximation in the Taylor series and the adaptation of the method to polychromatic sources through the discretization of the energy spectrum. For this purpose, an air tube with a Tungsten anode at 28kV was simulated. The results of simulations and experiments show that although the second-order approximation does not offer significant improvements over the original method (the CNR of the image did not improve beyond 5% compared to the original method), the adaptation for polychromatic sources does change the amplitude of the recovered phase, although it does not improve the resolution of the images. Additionally, a variant of the method is introduced to handle samples with multiple materials, which expands its applications in medical imaging diagnostics. This work highlights the robustness of the Paganin method in X-ray phase retrieval and suggests future directions for additional refinements, especially in managing spectral diversity and material differentiation in the analyzed samples.