Dose–volume characteristics of a 50-kV electronic brachytherapy source for intracavitary accelerated partial breast irradiation

Purpose To describe dose–volume data from a 50-kV electronic brachytherapy source in intracavitary accelerated partial breast irradiation. Methods and materials Three spherical balloon applicators were imaged on a CT scanner in a water phantom and inflated throughout their suggested fill volume range. The planning target volume (PTV) was defined as a 1-cm margin around the balloon surface. Plans were created achieving 80%, 85%, and 90% coverage of the PTV, with a prescription dose of 34 Gy in 10 fractions. The PTV, V90, V100, V150, V200, and V300 were recorded for each plan. Results For 80% target coverage, the V200 varies from 11 to 14 cm3 and the V150 from 26 to 49 cm3 over all the balloon applicators and fill volumes. For 85% coverage, the V200 varies from 14 to 18 cm3 and the V150 from 27 to 53 cm3. For 90% coverage, the V200 varies from 16 to 22 cm3 and the V150 cm3 from 30 to 61 cm3. Conclusions Fifty-kilovolt electronic brachytherapy can provide PTV coverage similar to 192Ir in the setting of intracavitary accelerated partial breast irradiation.