Brachytherapy, also called internal radiation therapy, involves placing radioactive sources (for example, radioactive seeds) inside the patient, directly into the tumor or the surrounding tissue. Because the radiation sources are placed so close to the tumor, doctors can deliver a large dose of radiation directly to the cancer cells with minimal exposure to normal tissue. These techniques are commonly used for treatment of prostate or gynecological (cervix, uterus or vagina) cancers.
The radioactive sources used in brachytherapy, such as thin wires, ribbons, capsules or seeds, come in small sealed containers. Some sources are placed permanently. These radioactive sources remain in the body after their radiation has been expended and the source is no longer radioactive. Other sources are placed temporarily inside the body, and the radioactive sources are removed after the prescribed dose of radiation has been delivered.