Multi-energy CT Reconstruction Algorithm For Complex Workpiece

The X-CT imaging technology has become an important non-destructive testing method.X-CT collects the projection data of the measured object from multiple angles,uses the reconstruction algorithm to solve the attenuation coefficient of the object,and finally reconstructs the internal structure of the object.However,in industry,many components have complex structures and great difference in material density.In CT reconstruction system based on fixed voltage,the projection data often appears overexposed or underexposed because of the limited dynamic range when complex workpiece is rayed.As a result,it leads to the lack of effective projection.And it is difficult to accurately reconstruct the internal structure of objects.To overcome problem of under sampled projection with single energy,in this paper,multi-energy CT reconstruction algorithm for complex components is studied based on the characteristics of complex components.Recursive iteration method is used to reconstruct multiple energy projections to achieve the purpose of complete component reconstruction and further improve image quality.The details are summarized as follow.The prior image constrained compressed sensing(PICCS)CT reconstruction based on multi-energy has been studied.During the process of reconstruction,the ART iterative algorithm is utilized to reconstruct the image,and the adjacent low-voltage reconstruction image is regarded as the original image in reconstructing.The objective function of PICCS is utilized to optimize the image when reconstruction is completed each time.Repeat the above steps until the highest energy.The results of the experiment show that the algorithm can effectively protect the low-density edge,reconstruct the internal structure of the object completely,and control the artifacts effectively.(2)The low-energy reconstruction image can not provide the structure information of the thick region,in order to ensure the accuracy of the prior image,the multi-energy CT reconstruction algorithm is proposed base on PICCS.The algorithm is to optimize the prior image constrained compressed sensing CT reconstruction based on multi-energy.Firstly,the prior image is segmented.The similar part of image is used as a priori image,the dissimilar and background of image is reconstructed with ART algorithm and POCS-TV algorithm respectively.Simulation results prove that the proposed algorithm can not only precisely reconstruct the whole internal structure of the object,but also play a certain role in maintaining the stability of pixels,and improve the image contrast.The reconstruction results of real projection data prove the practicability of the algorithm.