The Study Of Limited Angle CT Reconstruction Algorithm Based On Multi-objective Optimization

In the ICT, the phenomenon of limited-angle, truncated projection and hollow projection come out for the projection data because of the restrict of test conditions, motif size, motif structure and other factors. The problem of limited-angle is caused by the lack of projection information with the less of half circle in the conventional circular orbit scanning process. There are artifacts and the image resolution is low by using the analytic algorithm and the general iterative algorithm.In the paper, the reconstruction algorithm from limited-angle is mainly studied. First,we select three criterion such as least squares criterion, local entropy criterion and smooth criterion to build the multi-objective optimization model by using the multi-objective optimization theory. Second, the weight coefficient can affect the solution speed and even affect the accuracy of the solution. So in order to fix the weight coefficient efficiently to speed up the convergence rate of solution, the homotopy theory of topology has been introduced. According to the conception of homotopy mapping and homotopy parameter, we introduce the homotopy multi-objective optimization into the limited-angle image reconstruction. As a result the speed has been picked up by using the model of homotopy multi-objective optimization built by using the boundness of homotopy parameter. In the last, the simulation experiments have been carried out to prove the algorithm mentioned above. The reconstruction results and the analysis of data prove that the method which had been mentioned above is effective to solve the limited-angle reconstruction problem.