A novel methodology for the diffusion coefficient determination in porous media by X-ray high-resolution radiographies

The first step in diagnosing a patient with cancer is the biopsy and the study of the tissue sample taken, suitably processed, is essential for a correct diagnosis. Tissue processors are machines that automatically perform the entire processing protocol, often relying on empirical timing related to chemical diffusions in the biological samples. The determination of the diffusion coefficient in porous materials, such as histological tissue, is still under study with multiple methods often resulting in inaccurate predictions and with few amounts of literature data for biological samples. The authors present an experimental technique, based on a multitude of X-ray radiographs acquired over time, where the intensity of the attenuation to the ionising beam is proportional to the concentration of the solvent that diffuses in the histological preparation. The paper so describes a proof-of-concept of a novel method to estimate the diffusion coefficient in a histological sample, based on the acquisition of time-dependent X-ray radiographs and the solution of an inverse diffusion problem.