Po‐Poster ‐ 27: An anthropomorphic study in evaluating scattered radiation at pediatric CT

Purpose: The object of this study was to evaluate the dose contribution resulting from scattered radiation in CT head scans for pediatric patients using a one‐year‐old anthropomorphic tissue equivalent phantom. The dose due to scattered radiation was calculated, and the distribution of scattered radiation was analyzed. Methods and Materials: The direct exposure values were measured from specifically tagged organs by wedging TLD chips into tissue equivalent plugs. The absorbed doses were calculated with the roentgen‐rad conversion factors for tissues of one year olds. Additionally, absorbed doses were measured for nearly all the radiosensitive organs and tissues, inside and outside the scanned volume. The attribution of the scattered radiation was analyzed. Results: Two scan techniques were selected: 12mm and 20mm collimation head scans, both imaged at 120 kV. Scattered radiation contributed nearly 15 % to the total effective dose for both scanning techniques. The absorbed organ doses due to scattered radiation decreased exponentially as a function of the distance from the scanned volume. Conclusions: Scattered radiation had an appreciable contribution to the total effective dose. Pediatric radio‐sensitive organs close to the scanned volume could potentially receive relatively high absorbed doses, as determined from our study. It was also shown that absorbed doses due to scattered radiation fell exponentially, the further the organs from the irradiated volume. Further studies are required to understand the dependence of scatter on pediatric age, and CT technique factors.