X射线光栅相衬成像对弱吸收物质成像能够获得较高的图像衬度, 然而使用高分辨探测器, 成像时间长。此外, 受光栅工艺限制, 成像能量通常在30 keV左右。文中基于投影成像原理, 大大放宽了对光栅工艺的要求, 提高了成像能量。同时, 利用医用CT球管以及医用探测器, 基于周步进扫描模式, 实现了快速相衬CT成像。在国家同步辐射实验室搭建的成像系统上, 完成了80 kV管电压(等效能量约48 keV)180 mA管电流, 物体80 s曝光的二维和三维成像实验。针对实验结果, 进一步探讨了提高密度分辨率的方法和途径。

Although X-ray grating-based phase contrast imaging enables to obtain high image contrast of weekly absorbing substance, the imaging time is too long, due to high resolution detector. Furthermore, the imaging energy is usually about 30 keV, because of the limitation of grating manufacturing technique. In this paper, the requirement of grating manufacturing technique was relaxed sharply, thus the imaging energy was increased, based on the principle of projection imaging. In addition, fast phase contrast computed tomography (CT) imaging was realized on account of cycle-step-cycle mode, using medical CT tube source and medical detector. Experiments were carried out with tube voltage 80 kV, tube current 180 mA and 80 s exposure time to substance on the imaging system at National Synchrotron Radiation Laboratory. Last, how to improve the density resolution of the imaging system was discussed.