risk estimation of thyroid cancer for children undergoing brain ct examinations

Background: despite significant diagnosis benefits, the usage of ionizing radiation is not risk-free. the aim of this study was to determine the risk of thyroid cancer for children who exposed to brain computed tomography (ct) scan. method: in this cross-sectional study, 90 patients under 20 years of age who underwent brain ct-scan were selected. parameters such as age, sex, imaging technique, imaging characteristics, and thyroid absorbed dose were considered. we used spss software, version 21, at 95% confidence interval to analyze the absorbed dose and risk for each individual. results: the mean and standard deviation of absorbed doses for girls and boys for the spiral technique were 3.954±0.393 and 4.72±0.000 mgy, and in sequential technique, were 2.282±0.461 and 1.985±0.431 mgy, respectively. the mean and standard deviation of the absorbed doses in <5 years age group were 5.65±2.00, 3.03±1.34 in 6 to 10 years, 2.63±0.98 in 11 to 15 years, and in 16 to 20 years were 2.57±1.04 mgy (p < 0.001). there was a significant negative correlation between the absorbed dose and field dimensions (r = -0.604, p < 0.001) and slice thickness (r = -0.777, p < 0.001). the mean and standard deviation of lifetime risk for thyroid cancer induction (×105) in <5 years age group in spiral technique was 158.79±322.50 for female subjects and 16.5±42.90 for male patients, which was significantly more than those of other groups and techniques (p < 0.001). conclusion: the rate of thyroid absorbed dose during brain ct-scan was found to be noticeable, especially in spiral ct imaging, for female patients < 5 years. based on our results, it was associated with an increased risk of thyroid cancer in this age group.