大尺寸构件工业CT成像方法

为解决大尺寸构件快速ICT(Industrial Computed Tomography)成像问题,提出了一种通过检台2次偏置扩大扫描视场的ICT成像方法,并基于三代ICT投影数据存在的冗余特征,推导了它的投影数据重排预处理方法和滤波反投影(FBP,Filter Back-Projection)重建算法.该重排预处理方法建立了扇束投影数据与平行束投影数据间的函数映射关系,可将探测器在2个扫描位置采集的2组不完整扇形射束投影数据重排成一组完整的平行射束投影,从而使后续重建得以进行.计算机仿真结果表明,该方法在重构大尺寸构件图像时,获得了满意的质量.分析表明,在增加一次360°回转扫描情况下,其有效扫描视野达到标准三代ICT方法的2.8倍左右.该方法仅需CT扫描台具备平移和旋转自由度,易于与现有三代ICT兼容,工程实现方便. 

Industrial CT imaging method for large objects

An industrial computed tomography(ICT) imaging method to enlarge the field of view was proposed to execute the rapid CT test of large objects.Its projection data rebin pre-processing method and filter back-projection reconstruction algorithm were deduced.The pre-processing method is from the fact that there exists the data redundancy for 3rd scan ICT.It creates the function mapping relationship between fan beam projections and parallel beam projections. This method can rebin the two groups of incomplete fan beam projections acquired by the detector at two positions into one group of complete parallel beam projections to meet the requirement of the reconstruction algorithm.The computer simulation results prove the validity of the proposed method to large objects.Analysis shows that its field of view is 1.8 times larger than that of 3rd scan ICT.This method can be implemented with the table with the transverse movement and the rotation movement and is easy to compatible with 3rd scan ICT without extra hardware requirements.