Research on the CT image reconstruction of steel tube section from few projections

Most parameters of steel tube can be acquired from the computer tomography (CT) image of its section. However, a large number of projections are needed to reconstruct the image, so the collection and calculation of the projection data consume too much time to inspect steel tube online. For the purpose of solving the problem, we adopt the CT system that can collect the projection data without mechanical scanning motion and propose a modified penalized exponential EM (PEEM) algorithm to reconstruct the steel tube section from only three projections. In the method, the image area is restricted and the pixel value is binarized in order to decrease the number of projections needed and accelerate the convergence speed. At last, the problems of flaw inspection, influence of the restricted area and spatial resolution are discussed. The experiment results show that the accuracy and the reconstruction time of the algorithm meet the requirements of online inspection of steel tube, so it might be possible to be used in practical production.