CBCT Dose Is Reduced with Angular Tube Current Modulation While Maintaining Image Quality and Reducing Photon Starvation Artifacts.

PURPOSE: This study evaluated whether scout-derived angular tube current modulation (ATCM) in cone beam computed tomography (CBCT) can reduce radiation dose while preserving image quality. ATCM is routine in helical CT but remains absent from clinical CBCT and is largely unexplored in the literature.

METHODS

A projection-based intensity-dependent noise model was developed using polymethyl methacrylate slab measurements at 80-120 kV. Posterior-anterior and lateral scout views were used to derive angle-dependent elliptical attenuation estimates and to derive per-angle current-time product profiles. ATCM was emulated using projection data acquired with a clinical CBCT system and tested using anthropomorphic phantoms and a uniform water phantom. Dose-area product (DAP), effective dose based on Monte Carlo calculations, image noise magnitude, and noise texture were compared between modulated and unmodulated reconstructions. Image quality was subjectively evaluated by five board-certified radiologists using blinded paired preference scoring (60 paired reads; 12 pairs × 5 radiologists).

RESULTS

ATCM reduced DAP by up to 17% and effective dose by up to 20%, while maintaining image quality and noise texture, with improved reader preference in specific protocols. Modulated reconstructions showed reduced photon starvation artifacts in high-attenuation projection views and improved delineation of thoracic vertebra in selected protocols. Radiologists preferred ATCM in 60% of paired comparisons, most consistently for torso and jaw protocols (80 and 60% of paired comparisons, respectively).

CONCLUSION

Scout-derived ATCM for CBCT enables dose reduction while maintaining image quality, with improved reader preference in specific protocols, and reduced artifacts.