X射线束点尺寸对X射线相位衬度成像的影响  

Impact of Beam-Width on X-ray Phase-Contrast Imaging: A Simulation and Experimental Study

作　　者：江寿桂 雷威[1] 朱卓娅[1] 王昕[1] 张晓兵[1] Jiang Shougui;Lei Wei;Zhu Zhuoya;Wang Xin;Zhang Xiaobing(Joint International Research Laboratory of Information Display and Visualization,Southeast University,Nanjing 210096,china;School of Mathematics,Southeast University,Nanjing 210096,China)

机构地区：[1]信息显示与可视化国际合作联合实验室,东南大学南京210096 [2]东南大学数学学院,南京210096

出　　处：《真空科学与技术学报》2019年第3期268-272,共5页Chinese Journal of Vacuum Science and Technology

基　　金：国家重点研发计划项目(2016YFB0401600;2017YFC0111500;2016YFB0401600);国家自然基金项目(61674029;61775034;61775035;61571124);自然基金海外青年基金项目(61750110537)

摘　　要：X射线相位衬度成像利用X射线穿过样品后的相位变化,通过衍射信息来获得样品的结构特征。X射线相位衬度成像在生物影像、显微成像以及材料科学研究中有重要的应用。如果X射线成像样品物质密度比较低,它对X射线的吸收很小,所以常规的吸收衬度成像质量较差,不易分辨样品的结构细节。理论分析和实验研究都表明当X射线束点尺寸减小到一定尺度后,X射线源的空间相干性增强,采用相位衬度成像可以提高低密度样品的成像质量。X射线相位衬度成像质量与X射线束点尺寸,样品到影像记录平面之间距离直接相关。本文研究了X射线束点尺寸与低密度样品影像边沿轮廓宽度和对比度之间的影响关系。研究结果表明,根据低密度样品的介电常数、X射线源到样品距离,以及样品到影像记录平面距离,存在最优化的X射线束点尺寸。在该最优化配置条件下,低密度样品的X射线成像可以获得最好的图像质量。We addressed X-ray phase-contrast imaging(XPCI),suitable for imaging low density bio-organic,polymer and fibric materials.The influence of the imaging conditions,including the X-ray beam-width,sample/source separation,sample/screen distance,edge's contour-line width and dielectric-constant of sample,on the XPCI fine structures was mathematically modeled,theoretically analyzed,numerically simulated and experimentally evaluated.The simulated results show that depending on the sample's alignment and properties,the X-ray beam-width has a major impact.The measured and simulated results were in good agreement.For example,too small a beam-width decreases the edge's contour-lines width due to strong spatial X-ray coherence and a beam-width too large reduces the contrast of edge's contour-line.Hence the fine structures can be well observed with a moderate or optimized X-ray beam-width.We suggest that X-ray beam-width should be optimized according to the dielectric constant and alignment of a specific sample.

关 键 词：X射线相位衬度成像 低密度样品 X射线束点尺寸 成像质量 

分 类 号：O443.41[理学—电磁学]