- Synthetic radioisotope
A synthetic radioisotope is a
radionuclidethat is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. Examples include technetium-95 and promethium-146. Many of these are found in, and harvested from, spent nuclear fuel assemblies. Some must be manufactured in particle accelerators.
Some synthetic radioisotope are extracted from spent
nuclear reactorfuel rods, which contain various fission products. For example, it is estimated that up to 1994, about 49,000 TBq (78 metric ton) of technetiumwas produced in nuclear reactors, which is by far the dominant source of terrestrial technetium. inote|Topics in current chemistry, vol 176, "Technetium in the environment" However, only a fraction of the production is used commercially. Other synthetic isotopes are produced in significant quantities by fission but are not yet being reclaimed. Other isotopes are manufactured by neutronirradiation of parent isotopes in a nuclear reactor (for example, Tc-97 can be made by neutron irradiation of Ru-96) or by bombarding parent isotopes with high energy particles from a particle accelerator. [ [http://www.bnl.gov/medical/Isotope_Distribution/Isodistoff.htm Brookhaven National Laboratory, Medical Department, "Radioisotope Production."] ]
Most synthetic radioisotopes are extremely radioactive and have a short
half life. Though a health hazard, radioactive materials have many medical and industrial uses.
The general field of
nuclear medicinecovers any use of radioisotopes fordiagnosis or treatment.
Radioactive tracer compounds are used to observe the function of various organs and body systems. These compounds use a chemical tracer which is attracted to or concentrated by the activity which is being studied. That chemical tracer incorporates a short lived radioactive isotope, usually one which emits a
gamma raywhich is energetic enough to travel throughthe body and be captured outside by a gamma camerato map the concentrations. Gamma cameras and other similar detectors are highly efficient, and the tracer compounds are generally very effective at concentrating at the areas of interest, so the total amounts of radioactive material needed are very small.
nuclear isomerTc-99m is a Gamma-emitter widely used for medical diagnostics because it has a short half-life of 6 hours, but can be easily made in the hospital using a "technetium-cow".
Radiopharmaceuticals are any of a number of compounds using a radioisotope for medical treatment, usually by bringing the radioactive isotope to a high concentration in the body near a particular organ. For example, iodine-131 is used for treating some disorders and tumors of the thyroid gland.
Industrial radiation sources
Alpha particle, beta particle, and gamma rayradioactive emissions are industrially useful. Most sources of these are synthetic radioisotopes.
* [http://t2.lanl.gov/data/map.html Map of the Nuclides at LANL T-2 Website]
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