双能X射线光栅相衬成像系统具有成像效率高、辐射小、无须步进装置、成像平台简单等优点。研究了不同X射线能量下,CsI厚度与荧光透射率、金属铋的厚度与光强透射率的关系。基于以上研究,设计了一种双能分析光栅,阐述了光栅结构及栅条的制作材料,分析了栅条厚度的计算方法。对双能分析光栅成像进行了仿真,结果表明,设计的双能分析光栅可以获得清晰的条纹图像,并具有良好的条纹对比度。将设计的双能分析光栅应用于双能X射线光栅相衬成像系统,对成像系统进行了仿真,成像系统可以获得被测物体的相位一阶导数图像,表明设计的双能分析光栅是有效的。

The dual energy X-ray grating phase contrast imaging system exhibits a variety of advantages, including high imaging efficiency, low radiation, setups without stepping device, and simple imaging platform. Under different energy levels of X-ray, the relationship between the CsI thickness and the fluorescence transmittance, and the relationship between the Bi thickness and the transmittance of X-ray are studied. Based on the above research, a dual energy analysis grating is designed. The grating structure and the fabrication materials of the gratings are described, and the calculation method of the thickness of the grating bar is analyzed. The simulation of dual energy analysis grating is carried out. The results show that the designed dual energy analysis grating can obtain clear fringe image, and it has good fringe contrast. The designed dual energy analysis grating is applied to dual energy X-ray grating phase contrast imaging system. With simulation, the imaging system can obtain the phase first order derivative image of the measured object, indicating that the designed dual energy analysis grating is valid.