2014 年 50 巻 9 号 p. 633-639
X-ray CT is one of the most important diagnostic techniques which can generate cross-sectional images of an object. However, X-ray CT is still facing some technical issues; in particular, metal artifacts are a significant problem in CT imaging. A metal artifact is a radial noise caused by a discrepancy of projection data, and makes it difficult to diagnose patients with metal implants in their body. Even though various studies to reduce metal artifacts were conducted, the problem is not resolved yet. Therefore, the purpose of this study is to propose a method to reduce metal artifact, so as to widely disseminate a superior diagnostic technology. First, we propose a method for two dimensional CT data in this paper. The proposed method is divided into three processes, metal extraction, non-metal interpolation, and synthesizing. The algorithm is highly effective in metal artifact reduction because it is not sensitive to the discrepancy of projection data. And then, we extend the method to three dimensional CT data, and evaluate the effectiveness.