Radiation therapy uses high level ionizing radiation (such as gamma rays or beta particles) to treat diseases that are susceptible to such radiation. The radiation can be produced artificially (as with a particle accelerator) or with the use of highly radioactive isotopes, such as Cobalt-60. It is almost exclusively used for patients with cancerous tumors that cannot be removed surgically or treated with chemotherapy. It does have some other uses, such as to treat certain immune system disorders. However, radiation therapy is always dangerous to the patient and radiation sickness is a common side effect of such treatment. As such, a balance between enough exposure to the radiation to destroy the affected tissue without hurting healthy tissue must be reached.
Traditionally, patients were exposed to a narrow beam of radiation in an environment isolated from medical personnel. However, new methods use several less powerful beams from different directions aimed at a narrow point to increase the radiation dose to the tumor and lessen exposure to surrounding tissue.
Radiation seeding, which uses very small amounts of radioactive metal, allows radiation be placed directly inside the patient's body. This method tends to use high-radiation short half-life radiation sources, which will quickly lose their radioactivity and must be replaced at regular intervals.
Radiation is used instead of surgery where:
- the tumor is located in a place inaccessible to surgery; or
- surgery is likely to damage nerves or other tissues.
Radiation therapy is used to disastrous effect in House Training.