An in vitro comparison of the accuracy of measurements obtained from high- and low-resolution cone-beam computed tomography scans.

Introduction: This study aimed to investigate in an ex vivo model the reduction in patient radiation dose while maintaining accurate linear measurements by comparing cone-beam computed tomography (CBCT) scans taken at 360° versus 180° rotation, with porcine jaw specimens as a reference standard.

Methods: CBCT scans of 12 sectioned porcine hemimandibles at 360° and 180° rotations were taken with standardized clinical exposure parameters. To assess interobserver variability, 6 assessors who were blinded to the degree of rotation took linear measurements of anatomic structures on each scan. The measurements were repeated after 2 weeks to assess intraobserver variability. Accuracy of measurement was judged against the corresponding measurements taken from the porcine jaw specimens.

Results: Intraclass correlations signaled good-to-excellent intraobserver and interobserver agreement (0.65-0.98 and 0.79-0.98), respectively. Mixed regression analysis found no significant difference between the measurements from 180° or 360° rotations and no difference between the 2 rotations and porcine jaw specimens.

Conclusions: A CBCT image sufficient to make accurate clinical measurements with a reduced radiation exposure may be obtained by using 180° rotation of the CBCT tube head.