Gantry tilt as a dose reduction strategy for radiosensitive organs in pediatric brain CT: a prospective TLD study

Brain computed tomography (CT) is commonly performed in pediatric patients; however, radiation exposure to radiosensitive organs such as the lens and thyroid remains a major concern. This prospective study investigated the impact of gantry tilt on organ doses using thermoluminescent dosemeters. A total of 67 pediatric patients undergoing brain CT were divided into four age groups: 0-18 months, 18 months-5 y, 5-10 y, and 10-17 y. In vivo lens and thyroid doses were measured with and without gantry tilt, and their correlation with volume CT dose index (CTDIvol) was assessed. Significant positive correlations were observed between CTDIvol and both lens and thyroid doses. With gantry tilt, mean lens doses were 2.19-5.73 mGy and thyroid doses 0.68-0.99 mGy, compared with 10.89-29.30 mGy and 1.29-3.72 mGy, respectively, without tilt. Gantry tilt parallel to the supraorbital-meatal baseline substantially reduced organ doses, particularly to the lens, and should be considered as a practical optimisation technique in pediatric neuroimaging.