ISOTOPES USED IN MEDICINE

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Reactor Radioisotopes

Molybdenum-99: Used as the 'parent' in a generator to produce technetium-99m, the most widely used isotope in nuclear medicine.

Technetium-99m: Used in to image the skeleton and heart muscle in particular, but also for brain, thyroid, lungs (perfusion and ventilation), liver, spleen, kidney (structure and filtration rate), gall bladder, bone marrow, salivary and lacrimal glands, heart blood pool, infection and numerous specialised medical studies.

Chromium-51: Used to label red blood cells and quantify gastro-intestinal protein loss.

Cobalt-60: Used for external beam radiotherapy.

Copper-64: Used to study genetic diseases affecting copper metabolism, such as Wilson's and Menke's diseases.

Dysprosium-165: Used as an aggregated hydroxide for synovectomy treatment of arthritis.

Ytterbium-169: Used for cerebrospinal fluid studies in the brain.

Iodine-125: Used in cancer brachytherapy (prostate and brain), also diagnostically to evaluate the filtration rate of kidneys and to diagnose deep vein thrombosis in the leg. It is also widely used in radioimmuno assays to show the presence of hormones in tiny quantities.

Iodine-131: Widely used in treating thyroid cancer and in imaging the thyroid; also in diagnosis of abnormal liver function, renal (kidney) blood flow and urinary tract obstruction. A strong gamma emitter, but used for beta therapy.

Iridium-192: Supplied in wire form for use as an internal radiotherapy source for cancer treatment.

Iron-59: Used in studies of iron metabolism in the spleen.

Phosphorus-32: Used in the treatment of polycythemia vera (excess red blood cells). Beta emitter.

Potassium-42: Used for the determination of exchangeable potassium in coronary blood flow.

Rhenium-188 (derived from Tungsten-188): Used to beta irradiate coronary arteries from an angioplasty balloon.

Samarium-153: Very effective in relieving the pain of secondary cancers lodged in the bone, sold as Quadramet. Also very effective for prostate and breast cancer. Beta emitter.

Selenium-75: Used in the form of seleno-methionine to study the production of digestive enzymes.

Sodium-24: Used for studies of electrolytes within the body.

Strontium-89: Very effective in reducing the pain of prostate cancer. Beta emitter.

Xenon-133, Xenon-127: Used for pulmonary (lung) ventilation studies.

Yttrium-90: Used for cancer therapy and as silicate colloid for the treatment of arthritis in larger joints. Beta emitter.

Radioisotopes of palladium, caesium, gold and ruthenium are also used in brachytherapy.

Cyclotron Radioisotopes

Gallium-67: Used for tumour imaging and localisation of inflammatory lesions (infections).

Thallium-201: Used for diagnosis of coronary artery disease other heart conditions such as heart muscle death and for location of low-grade lymphomas.

Iodine 123: Increasingly used for diagnosis of thyroid function, it is a gamma emitter without the beta radiation of I-131.

Rubidium-81, Krypton-81m: Krypton-81m gas can yield functional images of pulmonary ventilation, e.g. in asthmatic patients, and for the early diagnosis of diseases and function of the lungs.

Indium-111: Used for brain studies, infection and colon transit studies.

Carbon-11, Nitrogen-13, Oxygen-15, Fluorine-18: These are positron emitters used in PET for studying brain physiology and pathology, in particular for localising epileptic focus, and in dementia, psychiatry and neuropharmacology studies. They also have a significant role in cardiology. F-18 in FDG has become very important in detection of cancers and the monitoring of progress in their treatment, using PET.