OBJECTIVES: The purpose of the study is to evaluate the effectiveness of thyroid shielding in dental CBCT examinations using a paediatric anthropomorphic phantom. METHODS: An ATOM(®) 706-C anthropomorphic phantom (Computerized Imaging Reference Systems Inc., Norfolk, VA) representing a 10-year-old child was loaded with six thermoluminescent dosemeters positioned at the level of the thyroid gland. Absorbed doses to the thyroid were measured for five commercially available thyroid shields using a large field of view (FOV). RESULTS: A statistically significant thyroid gland dose reduction was found using thyroid shielding for paediatric CBCT examinations for a large FOV. In addition, a statistically significant difference in thyroid gland doses was found depending on the position of the thyroid gland. There was little difference in the effectiveness of thyroid shielding when using a lead vs a lead-equivalent thyroid shield. Similar dose reduction was found using 0.25- and 0.50-mm lead-equivalent thyroid shields. CONCLUSIONS: Thyroid shields are to be recommended when undertaking large FOV CBCT examinations on young patients.
- cone beam computed tomography
- thermoluminescent dosimetry
- thyroid gland