Metal Artifact Reduction Method Based on Noncoplanar Scanning in CBCT Imaging

This study proposed a metal artifact reduction (MAR) method based on noncoplanar scanning for cone beam computed tomography (CBCT) imaging. Cylindrical aluminum and stainless steel bars were inserted into a phantom for cross-sectional and sagittal CBCT scanning. The metal bars were removed from scanning to obtain real CBCT images without metal artifacts. Corrected CBCT images were acquired after the artifact reduction of cross-sectional and sagittal images. Real CBCT images were used as the criteria, and the computed tomography value deviations of the original cross-sectional, sagittal, linear interpolation MAR (LIMAR), normalized MAR (NMAR), beam hardening correction (BHC) and proposed method were calculated. Most metal artifacts in the original image are removed in the corrected image, and thus, image quality is remarkably improved. The root mean square deviations of the original cross-sectional, sagittal, LIMAR, NMAR,BHC and proposed method are 122, 116, 90, 103, 92 and 85 HU, respectively, whereas their mean absolute deviations are 71, 73, 57, 55, 58 and 51 HU, respectively. The CT value deviation of the proposed method is the minimum. Conclusion: The proposed MAR method based on noncoplanar scanning can effectively reduce metal artifacts and improve CBCT image quality.