Interpolation Technology And Its Application In CT Reconstruction

X-ray CT has a wide range of applications in medicine,industry,security,materials,etc.However,in the process of CT image reconstruction,there may be many problems,such as poor quality of the reconstructed image due to insufficient projection data or loss of projection,and the appearance of ring artifacts and metal artifacts in the reconstructed image.At this time,interpolation technology can play an important role.In this paper,the new edge-directed interpolation method is applied to the projection domain of CT image reconstruction,the projection data is restored,and the filter back projection algorithm is used to reconstruct the image to solve the problem of incomplete projection data in CT sparse sampling,which leads to poor reconstructed image quality problem.Firstly,the basic knowledge of interpolation technology and CT image reconstruction required for the research of this subject is explained.First introduces the principles of nearest neighbor interpolation,bilinear interpolation,bicubic interpolation and new edge-directed interpolation and derives the corresponding interpolation formula;then introduces the development history of CT,CT imaging system,CT scanning method,projection and back projection,fourier center slice theorem,the filter back projection algorithm and image quality evaluation method.Secondly,the four image interpolation algorithms of nearest neighbor,bilinear,bicubic,and new edge-directed are compared and studied through image magnification experiments.First,directly down-sample the selected series of original images,and then use four interpolation algorithms to enlarge the down-sampled image to the same size as the original image.The evaluation experiment results show that the image quality after zooming based on the new edge-directed interpolation is better.Finally,the focus is on the sparse angle parallel beam image reconstruction based on the new edge-directed interpolation.Aiming at the problem of sparse angle parallel beam image reconstruction,four interpolation algorithms are used in the projection domain of CT image reconstruction.The missing projection data is restored by interpolating the projection domain,and then the filter back projection algorithm is used to reconstruct the image.The image reconstructed by the different algorithm was compared and studied.Experimental results show that,compared with the classic nearest neighbor interpolation,bilinear interpolation,and bicubic interpolation algorithms,the image quality reconstructed based on the projection data obtained by the new edge-directed interpolation algorithm is better.In order to further verify the reliability of the experimental conclusions,we consider adding noise to the projected sinogram,and then make an objective evaluation of the image reconstructed by the sinusoid filtered back projection after adding the noise.