X线位相对比成像中的位相信息

The phase information in X-ray phase contrast imaging

目的 探讨X线位相对比成像中的位相信息表达及其意义。方法 在北京同步辐射装置上 ,对组织密度差异小的生物样品和组织密度差异大的生物样品进行X线位相对比成像及传统的吸收对比成像 ,观察不同样品图像中的位相信息。结果 几种生物样品均获得了满意的位相对比图像。对于低吸收物体或组织密度差异小的物体 ,位相对比成像显示出一些吸收对比成像所无法显示的组织结构 ;而对于组织密度差异大的生物样品 ,位相对比成像使组织结构的边界更加清晰 ,显著地提高了图像的分辨力 ,能够清晰地显示生物样品中宽约 0 1mm的精细结构。结论 X线位相对比成像中位相信息突出表现为“界面强化效应” ,其价值在于显著地提高了图像的分辨力 ,并使得许多吸收对比成像所无法显示的组织结构被清楚显示。

Objective To study the expression of phase information in X-ray phase contrast imaging (XPCI) using synchrotron radiation and its significance. Methods We performed some experiments to obtain phase contrast images and absorption contrast images of several different biological objects in Beijing Synchrotron Radiation Facility (BSRF), then interpreted these images to find out the phase information in X-ray phase contrast imaging. Results The satisfactory phase contrast images of these experiment samples were acquired. XPCI of low-absorption objects or little absorption variation objects showed some structure that could not be demonstrated in absorption contrast images. For heavy absorption variation objects, XPCI made the margin of structure clearer, and the smallest microstructure we was able to distinguish was about 0.1 mm wide. The phase information was expressed as “white line”or“black line” around structure. Conclusion The phase information in XPCI manifests as “margin-enhanced effect”, and it dramaticanlly improves the efficiency and the resolution of the existing X-ray diagnostic techniques