Correction Of Metal Artifacts In CT Image

Computed Tomography (CT) is a new imaging technology which combines mechanical, automation, computer science and X-ray and other subjects. It has an extensive application on non harm medical diagnostics and non destructive testing because of the high spatial and density resolution of the CT images.As the metals in CT the scanned objects cause the inaccuracy of the project data so that there are light and white stripe artifacts in the CT reconstruction images, which are known as the metal artifacts. There artifacts seriously damage image quality and impact of the follow-up image processing and analysis. Therefore, the study of metal artifacts in CT image is an important issue, but also has been a hot issue to find a solution since the advent of X-ray CT.This article first introduces the theoretical basis of CT imaging and image reconstruction, analysis of the causes of metal artifacts, and then synthesizes and simulates the main home and abroad metal artifact correction method. Also optimizes some of the mainstream of the algorithms and analyzes the pros and cons of these algorithms. Finally a new adaptively hybrid filtering algorithm is proposed to reduce the artifacts caused by metal in CT image.In the new adaptive scaling hybrid algorithm, firstly an adaptive scaling and filtering method is used to preprocess the projection data of metal and the artifacts reduced image is reconstructed by filtered back projection (FBP) method. Then the expectation maximization algorithm (EM) is performed on the iterative original metal project data. Finally, a compensating procedure is applied to the reconstructed metal region. The simulation results have demonstrated that the proposed algorithm can remove the metal artifacts and keep the structure information of metal object effectively. It ensures that the tissues around the metal will not be distorted and reduces the threshold of accuracy of the impact. The method is also computational efficient and effective for the CT images which contains several metal objects. In addition, at end of the article the directions of the further study and improvement of the algorithm are proposed, through these studies will be possible to resolve the metal artifacts problems in the CT new technology and new applications.