Isotopes Used in Medicine-
Reactor Radioisotopes (half-life indicated)
- Molybdenum-99 (66 h): Used as the 'parent' in a generator to produce
technetium-99m.
- Technetium-99m (6 h): 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.
- Bismuth-213 (46 min): Used for TAT.
- Chromium-51 (28 d): Used to label red blood cells and quantify gastro-
intestinal protein loss.
- Cobalt-60 (10.5 mth): Formerly used for external beam radiotherapy.
- Copper-64 (13 h): Used to study genetic diseases affecting copper
metabolism, such as Wilson's and Menke's diseases.
- Dysprosium-165 (2 h): Used as an aggregated hydroxide for synovectomy
treatment of arthritis.
- Erbium-169 (9.4 d): Use for relieving arthritis pain in synovial joints.
- Holmium-166 (26 h): Being developed for diagnosis and treatment of liver
tumours.
- Iodine-125 (60 d): 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 (8 d): 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 (74 d): Supplied in wire form for use as an internal radiotherapy
source for cancer treatment (used then removed).
- Iron-59 (46 d): Used in studies of iron metabolism in the spleen.
- Lutetium-177 (6.7 d): Lu-177 is increasingly important as it emits just
enough gamma for imaging while the beta radiation does the therapy on
small (eg endocrine) tumours. Its half-life is long enough to allow
sophisticated preparation for use.
- Palladium-103 (17 d): Used to make brachytherapy permanent implant
seeds for early stage prostate cancer.
- Phosphorus-32 (14 d): Used in the treatment of polycythemia vera (excess
red blood cells). Beta emitter.
- Potassium-42 (12 h): Used for the determination of exchangeable
potassium in coronary blood flow.
- Rhenium-186 (3.8 d): Used for pain relief in bone cancer. Beta emitter with
weak gamma for imaging.
- Rhenium-188 (17 h): Used to beta irradiate coronary arteries from an
angioplasty balloon.
- Samarium-153 (47 h): Sm-153 is 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 (120 d): Used in the form of seleno-methionine to study the
production of digestive enzymes.
- Sodium-24 (15 h): For studies of electrolytes within the body.
- Strontium-89 (50 d): Very effective in reducing the pain of prostate and
bone cancer. Beta emitter.
- Xenon-133 (5 d): Used for pulmonary (lung) ventilation studies.
- Ytterbium-169 (32 d): Used for cerebrospinal fluid studies in the brain.
- Yttrium-90 (64 h): Used for cancer brachytherapy and as silicate colloid for
the relieving the pain of arthritis in larger synovial joints. Pure beta emitter.
- Radioisotopes of caesium, gold and ruthenium are also used in
brachytherapy.
- Cyclotron Radioisotopes
- 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.
- Cobalt-57 (272 d): Used as a marker to estimate organ size and for in-vitro
diagnostic kits.
- Gallium-67 (78 h): Used for tumour imaging and localisation of
inflammatory lesions (infections).
- Indium-111 (2.8 d): Used for specialist diagnostic studies, eg brain studies,
infection and colon transit studies.
- Iodine-123 (13 h): Increasingly used for diagnosis of thyroid function, it is a
gamma emitter without the beta radiation of I-131.
- Krypton-81m (13 sec) from Rubidium-81 (4.6 h): Kr-81m gas can yield
functional images of pulmonary ventilation, e.g. in asthmatic patients, and
for the early diagnosis of lung diseases and function.
- Rubidium-82 (65 h): Convenient PET agent in myocardial perfusion
imaging.
- Strontium-92 (25 d): Used as the 'parent' in a generator to produce Rb-82.
- Thallium-201 (73 h): Used for diagnosis of coronary artery disease other
heart conditions such as heart muscle death and for location of low-grade
lymphomas.
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