Speaker
Description
X-ray Phase Contrast (XPC) micro-CT enables imaging weakly attenuating samples that are challenging to image with conventional micro-CT. Our group focuses on mask-based XPC, using a highly attenuating mask upstream of the sample to shape the x-ray beam into beamlets. Attenuation and refraction by the sample then cause an intensity reduction and directional shift of the beamlets, respectively.
To detect these effects, a detector with sufficiently small pixels to resolve and “track” the beamlets can be employed; however, this can be impractical due to limitations in matrix size leading to small fields-of-view with high-resolution detectors. With larger-pixel detectors (e.g., common flat panels), tracking the beamlets requires a second mask creating an array of well-defined edges in front of the pixels; however, two exposures with different mask-detector alignments are required to quantitatively extract attenuation and refraction. Photon counting detectors offer reasonably large fields of view (e.g., 77.1 by 38.4 mm$^{2}$) while providing sharp transitions between pixels, removing the need for the second mask and allowing to quantitatively extract attenuation and refraction from a single exposure.
This talk will introduce a single-mask XPC system incorporating a photon counting detector (DECTRIS EIGER2 R 500K) and discuss how its properties can be exploited to improve image quality: on top of the absence of dark noise, ensuring ideal signal-to-noise, the lack of inter-pixel noise correlation enables self-supervised image denoising via Noise2Noise-style approaches. We also illustrate the system’s performance through an application in developmental biology, showing high-contrast images of mouse fetuses that reveal soft-tissue structures inaccessible with conventional micro-CT.