论文部分内容阅读
目的寻找螺旋CT测量误差的原因。方法6个金属小圆球(直径0.5mm)沿直线排列,间隔20mm,在与CT扫描定位线成0°、30°、60°、90°角时,分别行CT螺旋扫描,在CT图像上,测量6个金属小圆球之间的中心距离,以及6个金属小圆球的变形程度。改变重建中心位置,重复上述测量。结果在CT图像上,不同角度组、不同重建中心位置组,每2个相邻金属小圆球之间的中心距离均约为20mm,6个金属小圆球在不同情况下均发生同样的变形,呈米粒状改变,短径约2mm,长径约5mm,长径的轴线均与CT扫描床前进的方向平行,短径的轴线与长径垂直。结论CT测量误差与CT扫描后图像变形有关,而与物体在扫描野中所处的位置无关,与重建中心位置无关。物体的CT图像在扫描床前进方向上的变形程度较大,而在与前者垂直方向上的变形程度较小。
Objective To find out the reason of spiral CT measurement error. Methods Six small metal balls (0.5mm in diameter) were arranged in a straight line with a spacing of 20mm. CT scans were performed on the CT images at the angles of 0 °, 30 °, 60 ° and 90 ° with the CT scan. , Measuring the center distance between six metal spheres and the degree of deformation of six metal spheres. Change the location of the reconstruction center and repeat the above measurements. Results In the CT images, the center distance between two groups of adjacent metal spheres in different angle groups and in different reconstruction center positions was about 20 mm. The same deformation occurred in 6 metal spheres under different conditions , Changes in the form of rice, short diameter of about 2mm, long diameter of about 5mm, long axis of the CT scan with the bed in the direction of the forward parallel to the axis of short diameter perpendicular to the long diameter. Conclusion The CT measurement error is related to the image deformation after CT scan. It has nothing to do with the position of the object in the scan field and has nothing to do with the reconstruction center position. The CT image of the object has a greater degree of deformation in the advancing direction of the scanning bed and less deformation in the direction perpendicular to the former.