Quantitative evaluation of metal artifact reduction in CBCT under varying exposure modes and rod orientations

This study aimed to quantitatively evaluate the efficacy of a metal artifact reduction (MAR) algorithm in cone-beam computed tomography (CBCT) under varying exposure modes and metal rod orientations using a standardized evaluation method. A SEDENTEXCT IQ phantom was scanned with a CBCT system under three exposure modes (standard, low-dose, ultra-low-dose) and two rod orientations (horizontal, vertical), with the MAR algorithm activated and deactivated. Artifact areas were quantified from binarized images based on a thresholding method that distinguished artifact-affected regions from the background. The percentage reduction in metal artifacts was calculated by comparing scans acquired with and without MAR activation. Statistical analyses were conducted to assess differences across conditions. The MAR algorithm significantly reduced metal artifacts under all tested conditions (P < 0.05), with reductions of 61.5% in the standard mode, 73.6% in the low-dose mode, and 80.3% in the ultra-low-dose mode. By rod orientation, artifact reduction was 63.3% for the horizontal orientation and 80.7% for the vertical orientation. These results confirm the consistent effectiveness of the MAR algorithm across different acquisition settings. The proposed standardized evaluation method provides a reproducible framework for objectively assessing MAR performance and supporting its clinical integration.