The implementation of X-Ray Phase Contrast (XPC) imaging at synchrotrons has demonstrated transformative potential on a wide range of applications, from medicine and biology to materials science. However, translation to conventional laboratory sources has proven more problematic, because of XPC’s stringent requirements in terms of spatial coherence. This has imposed the use of either micro-focal sources, or collimators (e.g. source gratings) where sources with extended focal spots were used. This reduces the available x-ray flux leading to long exposure times, which is often exacerbated by the use of additional optical elements that need to be scanned during image acquisition. Where these elements are placed downstream of the object, they also lead to an increase in the delivered dose.
XPC has also been successfully adapted to full 3D, computed tomography (CT) implementations, which has however exacerbated the above concerns in terms of acquisition times and delivered doses.
We tackled this problem by developing an incoherent approach to XPC that works with non micro-focal laboratory sources without requiring any additional collimation. The method uses one or two low aspect ratio x-ray masks that are built on low-absorbing graphite substrates for maximum transmission through the mask apertures. The combination of this with a “single-shot” phase retrieval algorithm has enabled the development of a lab-based XPC-CT system that can perform a full scan in a few minutes while delivering low radiation doses. The talk will briefly describe how the method works, then show application examples including direct comparisons with the synchrotron gold standard.
Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has potential for applications in different fields of research, including materials science, non-destructive industrial testing, small-animal imaging, and medical imaging. One of its main advantages is the compatibility with laboratory equipment, in particular with conventional non-microfocal sources, which makes its exploitation in normal research laboratories possible. In this work, we demonstrate that the signal in laboratory implementations of EI can be correctly described with the use of the simplified geometrical optics. Besides enabling the derivation of simple expressions for the sensitivity and spatial resolution of a given EI setup, this model also highlights the EI’s achromaticity. With the aim of improving image quality, as well as to take advantage of the fact that all energies in the spectrum contribute to the image contrast, we carried out EI acquisitions using a photon-counting energy-resolved detector. The obtained results demonstrate that this approach has great potential for future laboratory implementations of EI.