Sara Baggio | Searcharxiv

arXiv2026

Fast Ptychographic Near-Field Computed Tomography

Near-field X-ray ptychography enables quantitative three-dimensional imaging with nanometer-scale resolution, but its broader application is limited by long acquisition times - often necessitating cryogenic or vacuum environments - and demanding sample preparation procedures. In this paper, we present a flexible near-field ptychography setup that operates under ambient conditions and features an adjustable geometry for different sample sizes and resolution requirements. By replacing stepwise angular acquisition with a fly-rotation sample motion, the scanning overhead is reduced by a factor of 11, drastically lowering the tomographic scan time. To address the bottleneck in sample preparation, we also introduce a sample milling machine that enables fast preparation of specimen pillars with diameters down to 20 um. By lowering both preparation effort and measurement time while maintaining high spatial resolution, the presented system overcomes key limitations of near-field ptychography and makes quantitative X-ray nanotomography substantially more accessible for biological research.

physics.optics↗

arXiv2025

Quantitative Stain Mapping in X-ray Virtual Histology

Virtual histology is an emerging field in biomedicine that enables three-dimensional tissue visualization using X-ray micro-computed tomography. However, the method still lacks the specificity of conventional histology, in which parts of the tissue are selectively highlighted using targeted stains. Though some first X-ray stains have been developed to address this issue, their precise location and quantity inside the tissue volume remain largely unknown. In this work, we present a novel approach to virtual histology that simultaneously captures electron number density and X-ray attenuation values through modulation-based X-ray imaging with a structured phase modulator. These complementary measurements enable decomposition of tissue volumes into basis materials, which allows the extraction of three-dimensional maps of molar contrast agent distribution alongside morphological details on the micrometer scale -- here demonstrated on murine kidneys. The concentration values are validated against the established method of K-edge subtraction imaging. We also create a direct bridge from X-ray to visible light imaging by detecting the same stain both using classical histology and our proposed X-ray approach. Our methodology opens new possibilities for biomedical research into disease progression by providing quantitative three-dimensional stain mapping across entire tissue volumes alongside high-contrast morphology, enabling deeper insights into disease mechanisms.

physics.med-ph↗