High angular sensitivity X-ray phase-contrast microtomography of soft-tissue through a two-directional beam-tracking synchrotron set-up

Two-directional beam-tracking (2DBT) is a method for phase-contrast imaging and tomography that uses an intensity modulator to structure the X-ray beam into an array of independent circular beamlets that are resolved by a high-resolution detector. It features isotropic spatial resolution, provides two-dimensional phase sensitivity, and enables the three-dimensional reconstructions of the refractive index decrement, $\delta$, and the attenuation coefficient, $\mu$. In this work, we report on the angular sensitivity and the spatial resolution of 2DBT images in a synchrotron-based implementation. In its best configuration, we obtained angular sensitivities of $\sim$20 $n$rad and spatial resolution of at least 6.25 $\mu$m in phase-contrast images. We also demonstrate exemplar application to the three-dimensional imaging of soft tissue samples, including a mouse liver and a decellularised porcine dermis.