锥束射线倾斜扫描三维层析算法

A Three Dimensional Reconstruction Algorithm of Cone Beam Scanning in Slantwise Direction

对于板、壳构件的无损检测,提出一种锥束射线倾斜扫描数字层析方法.采用射线相对于构件长宽表面倾斜入射、构件绕旋转轴回转的扫描方式,以采集的二维数字投影序列重构出该扫描区域的断层图像,给出了锥束射线倾斜扫描二维投影数值模拟算法以及滤波反投影重建算法.该重建算法为FDK算法的推广,在倾斜角90°时,该算法即为FDK算法.实验结果表明,该方法能较好地解决该类结构的层析检测,但由于该重建方法属于不完全投影数据重建,存在着相邻层之间的图像“混迭”现象,使得厚度方向上的分辨力有所降低.

A new reconstruction method was proposed for the non-destructive testing of shell-like or plate like obiects. With this method, X-rays irradiate to the surface of the reconstructed object at an oblique angle, a series of projection images are captured while the obiect is rotating. Then through relevant pre-processing method on the projections and special reconstructing algorithm, the cross-sections of the scanning region are finally got slice by slice. The projection data numerical simulation algorithm and filtering back projection reconstruction algorithm were proposed. The reconstruction algorithm can be regarded as generalized expression of FDK （Fieldkamp-Davis-Kress） algorithm, which means that when the oblique angle is 90°, the algorithm is as same as FDK algorithm. The experimental results prove that this method is good at solving the non-destructive testing of this kind of objects. But because this method is an incomplete reconstruction, the superimposed artifacts among adiacent slices are unavoidable, which decreases the resolution along axial direction.