Brachytherapy (brak-e-THER-uh-pee) is a procedure that involves placing radioactive material inside your body.Brachytherapy is one type of radiation therapy that's used to treat cancer. Brachytherapy is sometimes called internal radiation.Brachytherapy allows doctors to deliver higher doses of radiation to more-specific areas of the body, compared with the conventional form of radiation therapy (external beam radiation) that projects radiation from a machine outside of your body.Brachytherapy may cause fewer side effects than does external beam radiation, and the overall treatment time is usually shorter with brachytherapy.