变电压X射线多谱CT成像虚拟设计

Virtual Design of X-Ray Multi-Spectrum CT Imaging Based on Variable Voltage

复杂结构件在X射线成像时,由于射线透照方向上有效厚度差异大、成像器件动态范围受限等原因,单一电压下的射线图像易出现过曝光和欠曝光共存现象,投影信息缺失严重,无法进行CT重建,为此提出了变电压多谱CT成像理论与方法。通过改变电压改变X光谱分布,实现X光谱与检测对象有效厚度的匹配,扩展图像动态范围,确保检测对象投影信息的完整性;同时基于虚拟设计思想,建立了基于单能和多能的变电压虚拟CT模型,实现了变电压X射线CT成像的虚拟仿真。虚拟实验表明:变电压多谱CT成像原理是可行的,能够实现复杂结构件CT成像。

In the conventional X-ray imaging, the ray image of the complicated structural component （shape, structure complex and multi-materials） easily exhibits the overexposed and underexposed phenomenon. This is because of the bigger variations in the effective thickness in the orientation of X-ray penetration and the limit of the dynamic range of X-ray imaging system. The complete structure information can＇t be obtained, and it will impact the quality of X-ray CT image. So the present paper has improved the theory and method of variable voltage X-ray multi-spectrum CT imaging. The new method changes the distribution of X-ray spectrum by changing the voltage, and can realize the matching between the X-ray spectrum and the effective thickness of workpieces. This can expand the dynamic range and ensure the integrity of projection about the workpieces. At the same time, based on the idea of virtual design, the paper has built the variable voltage virtual CT mode based on single-energy and multi-energy, and realized virtual simulation of the variable voltage X-ray CT. At last, the virtual experiment has proved that the theory and method of variable voltage CT imaging is feasible, and the variable voltage CT imaging is the effective method for the complicated structural component.