锥束准三代三维工业CT成像方法研究

A Study on Cone-beam Quasi Generation Ⅲ 3D-ICT Imaging Method

基于FDK(Feldkamp,Davis and Kress)重建算法的圆轨道锥束扫描方式,因为算法的简洁性和工程实现的可行性,成为目前主要的三维工业计算机X射线断层摄影术(3D-ICT)成像技术。但受探测器长度的限制,该种技术的扫描视场小,可检构件尺寸受到限制。为解决较大尺寸构件3D-ICT检测问题,讨论了一种扫描锥束偏转的准三代3D-ICT成像方法,推导了它基于FDK原理的滤波反投影(FBP)重建算法。计算机仿真验证了该方法的正确性。分析表明,在扫描锥束偏转两次情况下,其有效扫描视野比圆轨道扫描方式提高1.4倍以上。

3D industrial computed tomography（3D-ICT） with circular orbit cone-beam scan mode based on Feldkamp Davis and Kress（FDK） reconstruction algorithm is considered more favorable for use than other processes. It is mathematically simpler and more feasible in engineering. However, limited by the length of detector, the technique has a smaller field of view. In order to execute the 3D-ICT inspection of large objects, a method called quasi generation Ⅲ 3D-ICT, which rotates the scanning cone beam, was discussed. Its filter back-projection reconstruction algorithm based on the FDK principle was deduced. The results of computer simulation prove the validity of the method. The analysis shows that the scanning field of view can be improved no less than 140 % compared with the circular orbit scan mode.