Attenuation filter-based metal artifact removing mixed reconstruction method for CT images

Abstract

The invention discloses an attenuation filter-based metal artifact removing mixed reconstruction method for CT images. When a CT acquires data, if a scanned object contains a metal object with high absorption coefficients which comprises a tissue attenuation coefficient and a metal attenuation coefficient to cause projection data jump, the scanned object is considered to be destructive and should be corrected; thus, the metal artifact is greatly weakened during FPB reconstruction. The method comprises the following steps: after determining a metal projection area, performing adaptive attenuation adjustment and filter on the determined metal area; reconstructing an entire image through the FBP, performing EM iterative reconstruction on the metal area by using the primary projection data, and correcting the metal area after the adaptive attenuation filter and reconstruction; and compensating the metal projection area. The numerical simulation CT experiments prove that the method can effectively remove metal artifacts and well keep the information of the metal and the surrounding tissue of the metal. Particularly under the condition of multiple metal objects, the method has low calculation complexity and high practical value.

Description

technical field [0001] The invention relates to the technical field of CT image processing, in particular to the technical field of eliminating metal artifacts. Background technique [0002] During the process of CT data acquisition, if the scanned object contains a metal object with a high absorption coefficient, the projection data will change suddenly. The projection data consists of two parts: one part is the tissue attenuation coefficient. The other part is the attenuation coefficient of the metal. This part of the projection data is generally considered "destroyed" and should be corrected, so that the metal artifacts are greatly weakened when reconstructed by FPB. The difference method and the hybrid method both remove the projection data of the metal area, and simply use the neighborhood interpolation data to replace the tissue of the metal area, which cannot truly reflect the attenuation coefficient of the tissue covered by the metal area, so the reconstructed by the...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to address the shortcomings of the current mainstream algorithms: the reconstruction image is distorted in the area around the metal; or the calculation amount of the algorithm is very large, resulting in a long reconstruction time and difficult to be practical

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