Thyroid radiation dose reduction with the use of thyroid shields during CT brain studies

Medical radiation plays a crucial role in diagnostic imaging; however, any exposure carries potential risks. The thyroid gland, due to its proximity to the imaging field, is particularly vulnerable to radiation during CT brain scans. This study aims to evaluate the effectiveness of lead thyroid shields in reducing the estimated absorbed dose to the thyroid gland during CT brain imaging. This cross-sectional study was conducted at a tertiary care hospital in Sri Lanka over a 3-month period. Adult patients referred for contrast-enhanced CT (CECT) brain scans, who underwent both non-contrast and contrast-enhanced imaging, were included. The estimated absorbed dose to the thyroid gland was calculated using a Dose i-R Electronic Personal Dosimeter. Radiation dose measurements were taken with and without a 0.5 mm lead thyroid shield by placing the dosimeter both above and behind the shield. The sample consisted of 32 patients. The mean (SD) effective radiation dose during the procedures was calculated as 2.325 (0.118) mGy using a standard conversion factor of 0.0021. Without the thyroid shield, the mean (SD) estimated absorbed dose was 0.748 (0.178) mGy, which decreased to 0.352 (0.113) mGy with the lead thyroid shield. There was a statistically significant reduction in estimated absorbed dose with the thyroid shielding. There was a significant reduction in the estimated absorbed dose to the thyroid region with the use of the lead thyroid shield in patients undergoing CT brain studies. These findings highlight the effectiveness of lead thyroid shielding in minimizing radiation exposure to the thyroid region.