Application of sensitive, high-resolution imaging at a commercial lab-based X-ray micro-CT system using propagation-based phase retrieval

Several dedicated commercial lab-based micro-computed tomography (CT) systems exist, which provide high-resolution images of samples, with the capability to also deliver in-line phase contrast. X-ray phase contrast is particularly beneficial when visualizing very small features and weakly absorbing samples. The raw measured projections will include both phase and absorption effects. Extending our previous work that addressed the optimization of experimental conditions at the commercial ZEISS Xradia 500 Versa system, single-distance phase-contrast imaging is demonstrated on complex biological and material samples. From data captured at this system, we demonstrate extraction of the phase signal or the correction of the mixed image for the phase shift, and show how this procedure increases the contrast and removes artefacts. These high-quality images, measured without the use of a synchrotron X-ray source, demonstrate that highly sensitive, micrometre-resolution imaging of 3D volumes is widely accessible using commercially advanced laboratory devices. Lay Description Commercial X-ray micro-computed tomography (micro-CT) devices allow for three-dimensional imaging of objects. At some of the systems, in-line phase-contrast imaging can be performed due to the high spatial resolution that they offer. Here, the so-called edge-enhancement effect based on the wave-optical properties of X-rays can be observed. In this case, the acquired images contain information on both the amplitude and the phase of the X-ray waves. Since the phase-shift induced by an object is very sensitive to small density variations, the imaging method is especially beneficial when looking at small features within low absorbing samples. In-line phase-contrast imaging usually requires to record radiographs with the detector being placed at several distances behind the object. In this work, the phase information is extracted from images that are acquired at only one detector distance. The experimental conditions to successfully perform this single-distance phase-contrast imaging technique at the Xradia 500 Versa system from Zeiss have been investigated. In addition, we showcase different application of the method on the examples of selected biological and industrial samples of complex (heterogeneous) composition. The results demonstrate that high-resolution and high-quality imaging of low-absorbing objects is not only possible at large-scale synchrotron facilities, but as well at laboratory systems. This enables an easy accessibility and a broad application of microscopic X-ray imaging in the future.