Answer to Question #1378 Submitted to "Ask the Experts"

Q

What are some specific radiosotopes used to cure various cancers? What are other ways radiation is used in medicine?

A

Question 1: What are some specific radioisotopes used to cure various cancers?

Answer 1: Iodine-131 is administered orally as a liquid or capsule in the treatment of thyroid cancer. Phosphorus-32 is instilled either in an intraperitoneal or intrapleural space to treat malignant effusions. Radioactive ⁸⁹Sr and ¹⁵³Sm are injected intravenously to relieve pain from bone cancers. Many radioisotopes are used as sealed sources to treat cancer such as ¹³⁷Cs, ¹⁹²Ir, ⁹⁰Sr, and ¹²⁵I. Cobalt-60 is used in a machine (teletheraphy unit) as a source of intense gamma radiation for the treatment of a variety of cancers.

Question 2: What are other ways radiation is used in medicine?

Answer 2: Medical uses of radiation include diagnosis of disease, therapy, and research. Diagnosis covers a wide range of exams from fairly routine x rays to complex CT scans and the injections of radioactive material for nuclear medicine imaging. In general, radiation therapy involves delivering a large dose of radiation to a small area of the body. Therapy is primarily directed to the killing of tumor cells as part of the treatment of cancer. Radiation therapy may also be used in the treatment of other diseases, such as coronary artery disease, by applying a large radiation dose to a small area on the inside surface of the vessel to reduce the probability that the artery will close (occlude) in the future. Radiation doses can be several millisieverts (mSv) for diagnosis and up to several sieverts (Sv) locally for treatments. The physician who prescribes radiation treatments and diagnosis weighs the risk of the radiation with the benefit of the treatment. Radiation (typically in very small quantities) is also used in research to find new ways to diagnose and treat disease. Jerrold Bushberg, PhD University of California, Davis