光学学报, 2017, 37 (4): 0434001, 网络出版: 2017-04-10
铋光栅X射线相衬成像条纹对比度的定量计算 下载: 513次
Quantitative Calculation of Fringe Visibility in Bismuth Grating-Based X-Ray Phase-Contrast Imaging
X射线光学 X射线相衬成像 条纹对比度 数值计算 铋吸收光栅 X-ray optics X-ray phase-contrast imaging fringe visibility numerical calculation bismuth absorption grating
摘要
吸收光栅是X射线相衬成像系统的关键器件,铋吸收光栅由于其制作成本低廉且适于在普通实验室开展制作而受到青睐。提出了一种针对铋光栅X射线相衬成像条纹对比度的定量计算方法,通过建立模型,数值计算了不同铋层厚度的吸收光栅所对应的叠栅条纹对比度,并比较了π和π/2相位光栅两种情形下的结果。结果显示,随着吸收光栅铋层厚度的增加,条纹对比度逐渐增加,当源光栅和分析光栅的铋层厚度分别达到150 μm和110 μm时,利用π相位光栅在40 kV管电压下其条纹对比度可达48%,60 kV管电压下其条纹对比度只能达到22%。而在两个吸收光栅铋层厚度相同的情况下,采用π/2相位光栅所得条纹对比度略优于π相位光栅的结果。对铋光栅X射线相衬成像条纹对比度的计算分析,可作为X射线相衬成像系统设计的参考依据,推动该成像技术走向实用化。
Abstract
Absorption gratings are the key devices in grating-based X-ray phase-contrast imaging (XPCI). The low cost and fitness for the fabrication in general laboratories make bismuth absorption grating favored. A calculating method for fringe visibility in bismuth grating-based XPCI is proposed, and the moire fringe visibilities of bismuth absorption gratings with different thicknesses are calculated through modeling. Results show that fringe visibility increases with the increasing thickness of bismuth structure. The fringe visibility for π phase grating can reach 48% under the 40 kV tube voltage, but only 22% under 60 kV, when the thicknesses of bismuth structure in source gratings and analyzer gratings are 150 μm and 110 μm, respectively. Furthermore, when the bismuth structure thicknesses of the two absorption gratings are equivalent, fringe visibilities are obtained by use of the π phase and π/2 phase gratings, respectively. Their quantitative comparison shows that the result of employing π/2 phase grating is slightly better than that of π phase grating. The quantitative calculation of fringe visibility will be beneficial to the design of grating-based XPCI system, which may promote the practicality of this technology.
黄建衡, 雷耀虎, 杜杨, 刘鑫, 郭金川, 李冀, 郭宝平. 铋光栅X射线相衬成像条纹对比度的定量计算[J]. 光学学报, 2017, 37(4): 0434001. Huang Jianheng, Lei Yaohu, Du Yang, Liu Xin, Guo Jinchuan, Li Ji, Guo Baoping. Quantitative Calculation of Fringe Visibility in Bismuth Grating-Based X-Ray Phase-Contrast Imaging[J]. Acta Optica Sinica, 2017, 37(4): 0434001.