具有方向性暗场灵敏度的实验室X射线微断层成像
Laboratory-based x-ray microtomography with directional dark-field sensitivity
AI总结：
本文提出基于双向光束追踪（2DBT）的实验室暗场X射线微断层成像方法，仅需单个光学元件即可在单次曝光下测量散射各向异性，实现微米级分辨率的三维无损结构表征，并在工程材料和生物组织成像中验证了其有效性。
摘要：
我们展示了一种在紧凑型实验室系统中实现的暗场X射线微断层成像方法，该系统能够在厘米级样品上以微米级分辨率解析衰减、相位和各向异性散射信号。该方法基于双向光束追踪（2DBT），仅需一个光学元件，并且与标准X射线源和探测器兼容。我们通过对一个定制构建的体模、一个纤维增强复合材料以及离体生物组织（包括牛椎间盘、大鼠心脏和猪半月板）进行成像，验证了该系统的能力。结果表明，暗场断层成像通过揭示远低于体素尺寸的长度尺度上的亚分辨率特征（如纤维取向和微结构异质性），为衰减以及相位断层成像提供了互补信息。我们系统的一个关键要素是其对图像平面内两个正交方向上的散射具有灵敏度，从而能够通过单次曝光测量散射各向异性。我们的方法不仅简单且稳健，而且灵敏且精确。这些发现证明了2DBT在工程、材料科学和生物医学应用中对样品和材料进行无损三维结构表征的潜力。
英文摘要：
We demonstrate dark-field x-ray microtomography in a compact, laboratory-based system capable of resolving attenuation, phase, and anisotropic scattering signals with micrometer-scale resolution across centimetre-scale samples. The method is based on two-directional beam tracking (2DBT), which requires only a single optical element and is compatible with standard x-ray sources and detectors. We validate the system's capabilities through imaging of a custom-built phantom, a fibre-reinforced composite and ex-vivo biological tissues, including a bovine intervertebral disc, a rat heart, and a porcine meniscus. The results show that dark-field tomography provides complementary information to attenuation as well as to phase tomography, by revealing sub-resolution features such as fibre orientation and microstructural heterogeneity at length scales that are well below the voxel size. A key element of our system is its sensitivity to scattering along two orthogonal directions in the image plane, enabling the measurement of scattering anisotropy with a single exposure. As well as simple and robust, our approach is sensitive and precise. These findings demonstrate the potential of 2DBT for non-destructive and three-dimensional structural characterisation of samples and materials in engineering, materials science and biomedical applications.
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