Abstract:Lung 4DCT is of great values in the application of tumor localization and individualized precise radiotherapy. However, due to the dose limitation, 4DCT data are in low resolution. In this paper, we proposed a patchbased superresolution reconstruction approach to enhance the resolution of 4DCT images. First, we divided the images into a number of overlapping patches. Then, Active Demons registration algorithm was utilized to adaptively select corresponding patches in each phase for the specific patch, and obtain the motion fields between the patches simultaneously. After that, iterative back projection (IBP) algorithm was adopted to reconstruct highresolution patch. At last, we assembled all patches into a final output high resolution image. A public dataset provided by the DIRlab at the University of Texas M.D. Anderson Cancer Center (Houston, TX) was employed to evaluate the proposed method. The dataset consists of 10 groups of lung 4DCT data, each group contains 10 phases. Images of different phases are selected to perform the above procedure for experiment. Quantitative evaluation results indicate that the proposed method significantly increases image average gradient value (892±050, P<0001) compared with back projection (BP) algorithm (765±044) and global IBP algorithm (792±043). Qualitative evaluation results also show that our approach can eliminate artifacts effectively and get clearer lung 4DCT images with significantly enhanced structures.
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