Wang Zhili, Shi Xiaomin, Ren Kun, Chen Heng, Ren Yuqi, Gao Kun, Wu Zhao
School of Electronic Science and Applied Physics, Hefei University of Technology, Anhui 230009, People's Republic of China.
Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, People's Republic of China.
J Synchrotron Radiat. 2020 Mar 1;27(Pt 2):494-502. doi: 10.1107/S1600577519017223. Epub 2020 Feb 26.
A three-image algorithm is proposed to retrieve the sample's transmission, refraction and dark-field information in hard X-ray grating interferometry. Analytical formulae of the three-image algorithm are theoretically derived and presented, and evaluated by proof-of-principle synchrotron radiation experiments. The results confirm the feasibility of the proposed algorithm. The novelty of the proposed algorithm is that it allows versatile and tunable multimodal X-ray imaging by substantially relaxing the existing limitations on the lateral grating position. Furthermore, this algorithm can also be adapted for samples with negligible refraction, reducing the number of required sample measurements to two. Furthermore, the noise properties of the retrieved images are investigated in terms of the standard deviations. Theoretical models are presented and verified by synchrotron radiation measurements. It is shown that the noise standard deviations exhibit strong dependence on the lateral grating position, especially in the case of refraction and dark-field images. Further noise reduction and dose reduction can thus be possible by optimizing the lateral grating position for a selected region of interest. Those results can serve as general guidelines to optimize the data acquisition scheme for specific applications and problems.
提出了一种三图像算法，用于在硬X射线光栅干涉测量中获取样品的透射、折射和暗场信息。从理论上推导并给出了三图像算法的解析公式，并通过原理性同步辐射实验进行了评估。结果证实了该算法的可行性。该算法的新颖之处在于，通过大幅放宽对横向光栅位置的现有限制，它允许进行通用且可调谐的多模态X射线成像。此外，该算法还可适用于折射可忽略不计的样品，将所需的样品测量次数减少到两次。此外，根据标准差对重建图像的噪声特性进行了研究。提出了理论模型，并通过同步辐射测量进行了验证。结果表明，噪声标准差对横向光栅位置有很强的依赖性，特别是在折射和暗场图像的情况下。因此，通过为选定的感兴趣区域优化横向光栅位置，可以进一步降低噪声和减少剂量。这些结果可为针对特定应用和问题优化数据采集方案提供通用指导。
