Measurement of dose perturbation around shielded ovoids in high-dose-rate brachytherapy.

Purpose: To analyze the effect of tungsten shields present in a Fletcher-Suit-Delclos ovoid by comparing the dose distribution computed by a treatment planning system (TPS) to the delivered dose distribution measured by radiochromic film dosimetry.

Methods And Materials: Gafchromic/EBT films were carefully wrapped around the caps (diameter 20-25 mm) of shielded as well as unshielded ovoids, including their anterior and posterior ends. The ovoids were irradiated to a dose of 300 cGy using a high-dose rate remote afterloading unit.