Effect of the Leaded Glasses as an Exomass Object on CBCT Images

Abstract

Objectives: To investigate the effect of artifacts in cone-beam computed tomography (CBCT) arising from leaded-glasses located in the exomass on detection of root fracture (RF) and MB2 canal, and to test different image-acquisition parameters to reduce them.

Methods: CBCT scans of a human cadaver head were acquired with the 3D-Accuitomo 170 utilizing FOV of 100 × 50 mm, which placed the leaded-glasses outside the field of view (FOV). Scanning parameters considered three conditions of standard/high resolution, full/partial rotations, with/without leaded-glasses. Six evaluators assessed the images for the presence of RF and MB2 and the quality of the images. For artifact measurement at different distances from the exomass, the standard deviation (SD) of grey values in three specified axial slices at different levels was obtained. The effects of the parameters and their interactions were evaluated by Analysis of Variance (α = 5%).

Results: Fixed effects, estimated for various resolutions, rotation 360°/180°, and the presence or absence of the exomass, were not statistically significant on detection of RF (i.e. these factors had no impact on the detection of RF). Exomass had a significant negative effect on identifying MB2 (i.e. the readers were less able to detect the MB2 where exomass were present). The fixed effects of the rotation 360°/180° and resolutions were not statistically significant. The effect of exomass on image quality was significantly negative, while the effects of wider arc and higher resolution was significantly positive. The closest slices to the exomass produced the highest standard deviation (SD) values (more heterogeneous gray values, corresponding to greater artifact expression), followed by middle, and farther slices. These findings demonstrated that the artifact intensity was negatively influenced by the presence of the exomass and by the image slice's distance to the exomass (p < 0.05).

Conclusions: Metallic exomass creates artifacts, which lower the image quality. The detection of RF is unaffected by exomass artifacts. Therefore, leaded-glasses may be worn by patients with suspected RF during CBCT scans to reduce the dose to the lens of the eye and lower the chance of developing cataract.