Dental Cone-Beam Computed Tomography: Are the Eye Lens and Thyroid at Risk?

Background: The purpose of this study was to assess radiation dose to the eye lens (EL) and thyroid gland (TG) from 22 protocols used in maxillofacial imaging with cone-beam computed tomography (CBCT). Methods and Results: NanoDot optically stimulated luminescence dosimeters were used to assess scattered radiation to the EL and TG using a phantom. The dosimeters were secured at four sites around areas of interest. Mean eye radiation dose was significantly associated with field of view (FOV) size (r=0.830, P < 0.001). Meanwhile, the mean thyroid radiation dose was found to be significantly associated only with exposure time (r=0.464, P=0.030). Mandible centralization was observed to be the most significant predictor for a greater effective thyroid dose; mandible FOV centralization had 0.236 odds of a higher thyroid dose than maxilla FOV centralization. Conclusion: FOV size significantly impacted EL dose. Thyroid exposure was affected by FOV centralization and exposure time. Centering the FOV on the mandible resulted in a greater effective dose due to the proximity of the TG to the primary beam.