X射线大视场相衬成像位移误差的数值分析

1)深圳大学光电工程学院,光电子器件与系统教育部/广东省重点实验室,广东深圳 518060; 2)深圳大学信息工程学院,广东深圳 518060

光学工程; X 射线; 相衬成像; 相位步进法; 位移误差; 视场

Numerical analysis of shift error in X-ray phase contrast imaging for large field of view
Huang Jianheng1,2, Lei Yaohu1, Liu Xin1,

Huang Jianheng1,2, Lei Yaohu1, Liu Xin1, Guo Jinchuan1, Li Ji1, and Guo Baoping11)College of Optoelectronic Engineering, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University, Shenzhen 518060, Guangdong Province, P.R.China2)College of Information Engineering, Shenzhen University, Shenzhen 518060, Guangdong Province, P.R.China

optical engineering; X-ray; phase-contrast imaging; phase stepping method; shift error; field of view

DOI: 10.3724/SP.J.1249.2017.01008

备注

随着X射线光栅相衬成像视场的扩大,相位步进法中的位移误差会对相衬图像造成很大影响.提出一种X射线大视场光栅相衬成像位移误差的数值分析方法,通过数值计算获得不同位移误差下两个聚苯乙烯小球的相衬成像结果.理论模型的数值计算结果表明,位移误差会导致小球相衬图像产生明暗条纹的背景干扰,位移误差越大,其相衬图像受背景条纹的干扰越严重.当位移误差达到光栅周期的1/10时,小球相衬信息几乎被背景条纹所淹没,致使其边缘信息无法识别.要获得背景均匀的大视场相衬图像,则位移误差最好控制在光栅周期的1/100以下.分析结果可为X射线大视场相衬成像系统的设计提供参考依据.

With the expansion of field of view(FOV)in grating-based X-ray phase-contrast imaging(XPCI), shift error in phase stepping method causes a great impact on the quality of phase-contrast image. A method is presented to analyze shift error in grating-based XPCI for large FOV, and the imaging results of two polystyrene spheres under different shift errors are obtained by numerical calculation. The results show that interferences of strip patterns appear in the background of phase-contrast images. The larger the shift error is, the more serious the interference becomes. When the shift error is up to 1/10 of the grating period, the edges of the spheres are unable to be identified from strip patterns. And shift error has to be set as less than 1/100 of the grating period to obtain a phase-contrast image without strip patterns for large FOV. The numerical analysis and discussion of shift error will be beneficial to the design of grating-based XPCI for large of view.

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