Brachytherapy is radiation delivered from radiation sources (radioactive materials) placed inside or on the body.
Doctors can use brachytherapy alone or in addition to external-beam radiation therapy to provide a “boost” of radiation to a tumor while sparing surrounding normal tissue. Brachytherapy may be able to deliver higher doses of radiation to some cancers than external-beam radiation therapy while causing less damage to normal tissue.
Several brachytherapy techniques are used in cancer treatment, based on locations of cancer, dose and period of treatment. Interstitial brachytherapy uses a radiation source placed within tumor tissue, such as within a prostate tumor. Intracavitary brachytherapy uses a source placed within a surgical cavity or a body cavity, such as the chest cavity, near a tumor. Episcleral brachytherapy, which is used to treat melanoma inside the eye, uses a source that is attached to the eye.
In interstitial brachytherapy, radioactive isotopes are sealed in tiny pellets, the size of a grain of rice. These seeds are placed in the body using delivery devices, such as needles, catheters, or some other type of carrier. As the isotopes decay naturally, they give off radiation that damages nearby cancer cells. If left in place, after a few weeks or months, the isotopes decay completely and no longer give off radiation. The seeds left in the body do not cause harm.
Brachytherapy can be given as a low-dose-rate or a high-dose-rate treatment. In low-dose-rate (LDR) treatment, cancer cells receive continuous low-dose radiation from the source over a period of several days to weeks. In high-dose-rate (HDR) treatment, a robotic machine (remote afterloader) attached to delivery tubes placed inside the body guides one or more radioactive sources into or near a tumor, and then removes the sources at the end of each treatment session. High-dose-rate treatment can be given in one or more outpatient treatment sessions.