Determination of Scattered Radiation to the Thyroid Gland in Dental Cone Beam Computed Tomography

Abstract

Background: Cone beam computed tomography (CBCT) is a specialized medical equipment and plays a significant role in the diagnosis of oral and maxillofacial diseases and abnormalities; however, it is attributed to risk of exposure of ionizing radiation. The aim of the study was to estimate and determine the amount of scattered radiation dose to the thyroid gland in dental CBCT during maxilla and mandible scan.Materials and Methods: The average scattered radiation dose for i-CAT 17–19 Platinum CBCT (Imaging Sciences International) was measured using a Multi-O-Meter (Unfors Instruments), placed at the patient’s neck on the skin surface of the thyroid cartilage, with an exposure parameter of 120 kVp and 37.07 mAs. The surface entrance dose was noted using the Multi-OMeter, which was placed at the time of the scan at the level of the thyroid gland on the anterior surface of the neck.Results and Discussion: The surface entrance dose to the thyroid from both jaws scans was 191.491±78.486 μGy for 0.25 mm voxel and 26.9 seconds, and 153.670±74.041 μGy from the mandible scan, whereas from the maxilla scan the surface entrance dose was 5.259±10.691 μGy.Conclusion: The surface entrance doses to the thyroid gland from imaging of both the jaws, and also from imaging of the maxilla and mandible alone were within the threshold limit. The surface entrance dose and effective dose in CBCT were dependent on the exposure parameters (kVp and mAs), scan length, and field of view. To further reduce the radiation dose, care should be taken in selecting an appropriate protocol as well as the provision of providing shielding to the thyroid gland.