The purpose of this study was to evaluate the effectiveness of metal artifact reduction (MAR) processing in cone beam computed tomography angiography using the relative artifact index (AIr) and the difference due to tube voltage. A water phantom was imaged to obtain noise images. Next, a platinum alloy embolic coil was installed in the central part of the water phantom and the peripheral part, and then artifact images were acquired. The tube voltages were 70 kV and 109 kV, and four types of artifact images were acquired (with and without MAR). In all, 10 images in the z-direction from each image series were acquired (total: 40 images). The AIr value was calculated by setting a region of interest in the images, and multiple comparisons were made between the imaging conditions (significance level set at p<0.05). The AIr values were significantly lower by MAR, and MAR significantly reduced metal artifacts regardless of tube voltage (p<0.001). This study's results show that MAR with cone beam CT can reduce metal artifacts by more than 91%, and the effect is comparable regardless of tube voltage.
Keywords: cone beam computed tomography (CBCT); metal artifact reduction (MAR); relative artifact index; tube voltage.