Evaluation of anode heel effect on gonadal dose during AP pelvic radiography using PHITS

Abstract

Anode heel effect is a radiographic phenomenon that produces a variation of intensity in the useful x-ray beam. This design of the anode target results in decreased radiation intensity on the anode side of the beam, which makes anode heel effect useful in imaging parts that are uneven in thickness.  Due to the discontinued use of  gonadal shielding from routine pelvic radiography procedures, this study investigated anode heel effect as an alternative way to optimize doses. Gonadal doses were calculated from adult and pediatric phantoms using Particle and Heavy Ion Transport code System (PHITS). Dose differences due to anode heel effect was calculated by exposing the phantoms in two different orientations: feet facing the cathode side, and feet facing the anode side. Results showed that all phantoms received greater gonadal doses when the feet are placed towards the cathode side. The obtained dose reductions showed that male gonads are more likely to be affected by anode heel effect due to its anatomical location.