Temporal bone image quality in CBCT: Device and protocol variations.

Objectives: Considering the high prevalence of temporal bone imaging and the growing tendency to replace the CT scan with CBCT in this field, it seems necessary to determine the optimal radiation conditions in each commercial CBCT brand to obtain the best diagnostic images with minimal patient radiation.

Methods: A dry human skull was imaged by 6 radiation protocols in 4 different CBCT devices. The images of anatomical landmarks including cochlea, lamina spiralis, facial canal, semicircular canals, and modiolus, were reconstructed. Then, the quality of these images was determined by 3 observers based on a 4-point scoring system. The Kappa coefficient was adopted to evaluate the observer's agreement, and the Kruskal-Wallis and Mann-Whitney tests were used to compare the mean scores of the protocols and the superiority of the protocols in each device, respectively.

Results: There was no statistically significant difference between the mean scores of the protocols in the Acteon and NewTom devices. In the Kodak and Planmeca devices, the recommended protocol for imaging the temporal bone is protocol 1 and protocol 3, respectively.

Conclusion: Considering the replacement of the CBCT device for temporal bone imaging and the variety of related protocols in these devices, to reduce the overall society dose, it seems necessary to conduct further studies to determine the optimal radiation conditions in each device. In addition, the ability to unilaterally image the temporal bone is an underappreciated advantage of the CBCT over the CT, which prescribers are not familiar with.