High Dose Breast Radiation
High-dose rate radiation (brachytherapy) lets doctors insert radioactive material directly in or near cancerous tissue. This internal radiation can dramatically shorten treatment time and may result in fewer side effects.
For breast cancer, radioactive seeds are inserted through a catheter directly in to your breast where the tumor was removed. The seeds deliver a highly targeted dose of radiation to this area, called the tumor bed, for a few minutes, and then they are removed. Catheter brachytherapy is done twice a day for five days. This is an out-patient procedure, so you can go home between treatments.
Doctors typically use high-dose breast radiation on smaller tumors with clear margins. It takes far less time than external beam radiation, which is given five days a week for five or six weeks.
National Cancer Institute: Radiation Therapy for Cancer