A vaginal brachytherapy applicator is versatile to different anatomies and more comfortable to the patient than prior applicators. An inflatable balloon on a shaft may be inelastic or elastic. In one embodiment the shaft is rotatable relative to the balloon for enabling a ring or band of dose delivery, for versatility in radiation placement. Alternatively, the source can be rotated and pulled back within a stationary shaft. An adjustment is provided for reducing the length of balloon that inflates, to accommodate different anatomies and positions. Although isotope radiation sources can be used in the applicator, an electronic source is preferred, and the system and method include procedures for using the applicator with an electronic source.