Image reconstruction method of dual energy CT for multilayer spherical shell with great density difference

The dual energy CT method can be used in nondestructive test for large size multilayer spherical shell with high density difference materials. Low Z materials basically have no barrier to high energy X-ray scanning, while low energy scanning will be truncated by high Z materials, hence image reconstruction methods need to be studied according to the dual energy X-ray projection features. The simulation model is designed according to the structure characteristics of the multilayer spherical shell, and projection sonograms for both high and low energy X-rays are simulated respectively, on this basis, images are reconstructed with Filtered Back Projection(FBP) or Algebraic Reconstruction Technique(ART) algorithm. Through a mass of simulation and comparative analysis, the conclusion is drawn that the F-R(fuse first and then reconstruct) method is better than the R-F(reconstruct first and then fuse) method for image reconstruction of the dual energy CT. It is pointed out that in order to ensure the image reconstruction quality, for the scanning X-ray energy choice, it is necessary not only to improve local projection quality, but also to minimize the total amount of the truncated projection.