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

Abstract 

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 34Gy 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 14cm³ and the V₁₅₀ from 26 to 49cm³ over all the balloon applicators and fill volumes. For 85% coverage, the V₂₀₀ varies from 14 to 18cm³ and the V₁₅₀ from 27 to 53cm³. For 90% coverage, the V₂₀₀ varies from 16 to 22cm³ and the V₁₅₀cm³ from 30 to 61cm³.

Conclusions

Fifty-kilovolt electronic brachytherapy can provide PTV coverage similar to ¹⁹²Ir in the setting of intracavitary accelerated partial breast irradiation.

Keywords: Breast cancer, Brachytherapy, Partial breast irradiation