Dose modification factor analysis of multilumen balloon brachytherapy applicator with Monte Carlo simulation.

The Contura brachytherapy applicator is a silicone balloon with five lumens in which a high-dose-rate brachytherapy source can traverse. Multilumen applicators, like the Contura, are used in accelerated partial breast irradiation (APBI) brachytherapy in instances where asymmetric dose distributions are desired; for example, when the applicator surface-to-skin thickness is small (< 7 mm). In these instances, the air outside the patient and the lung act as a poor scattering medium, scattering less dose back into the breast and affecting the dose distribution.