X-ray phase-contrast microtomography based on speckle tracking is an attractive method for non-destructive three-dimensional imaging owing to its simple setup and ability to yield absorption, refractive, and scattering images simultaneously. However, the edge-enhancement effect usually results in image artifacts or inaccurate phase retrieval, limiting the extensive application of this method in biomedical research and for low-Z materials. In this paper, a double-exposure method is introduced to solve this problem efficiently and accurately. Pure phase samples with various microstructures and densities and a biological sample with a distinct edge-enhancement effect were used to verify the effectiveness of the developed method. In an experiment performed using a polymer phantom with an evenly distributed density, 17 irregularly shaped particles with diameters ranging from 15 to 25 μm were successfully reconstructed with the effective elimination of the edge-enhancement effect. The results obtained for a sample composed of different polymer materials demonstrated that, in contrast with the traditional speckle-tracking method, the present method is able to discriminate materials with similar x-ray attenuations. Finally, experiments were performed using a dehydrated fish, which entail typical edge enhancement and a complex microstructure; notably, it was verified that the fine structure of the fish, including its fins and intestines, was reconstructed completely using the proposed method, whereas the standard speckle-tracking method was ineffective. In conclusion, the developed double-exposure method can serve as an efficient and accurate technique for the x-ray phase-contrast microtomography of samples comprising low-Z materials and complicated microstructures.

中文翻译：

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斑点跟踪x射线相衬显微断层扫描的双曝光方法

基于散斑跟踪的X射线相衬显微断层照相术是无损三维成像的一种有吸引力的方法，因为它的设置简单并且能够同时产生吸收，折射和散射图像。但是，边缘增强效果通常会导致图像伪影或不准确的相位恢复，从而限制了该方法在生物医学研究和低Z材料中的广泛应用。本文介绍了一种双重曝光方法，可以有效，准确地解决这一问题。使用具有各种微观结构和密度的纯相样品以及具有明显边缘增强作用的生物样品来验证所开发方法的有效性。在使用密度均匀分布的聚合物模型进行的实验中，通过有效消除边缘增强效果，成功重建了17个直径范围为15至25μm的不规则形状的颗粒。对于由不同聚合物材料组成的样品所获得的结果表明，与传统的散斑跟踪方法相比，本方法能够区分具有相似x射线衰减的材料。最后，使用脱水鱼进行了实验，这需要典型的边缘增强和复杂的微观结构。值得注意的是，已证实使用所提出的方法可以完全重建鱼的精细结构，包括其鳍和肠，而标准的斑点跟踪方法无效。综上所述，