Brachytherapy is a form of radiation where the radioactive source is brought close to the target tissue rather than treating it from a distance with a machine (called external beam irradiation).
Common types of brachytherapy include implanting radioactive seeds into a tumor. These seeds are left in permanently and give off radiation in a slow manner (called low dose rate radiation). Other techniques include implanting tubes of radium or cesium that will slowly radiate a tumor over a matter of hours.
New devices use highly radioactive isotopes that will treat a tumor in a matter of minutes and are referred to as high dose rate (HDR) devices. These devices have been used to treat gynecologic, lung and esophagus cancers.
More recently HDR techniques have been used to treat breast cancer, reducing a six-week course down to five days.