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In nuclear medicine, radioisotopes are used for diagnosis, treatment, and research. Radioactive chemical tracers emitting gamma rays or positrons can provide diagnostic information about internal anatomy and the functioning of specific organs, including the human brain.
This page lists radioactive nuclides by their half-life.
About 338 nuclides are found naturally on Earth. These comprise 251 stable isotopes, and with the addition of the 35 long-lived radioisotopes with half-lives longer than 100 million years, a total of 286 primordial nuclides, as noted above.
Radioisotopes of iodine are called radioactive iodine or radioiodine. Dozens exist, but about a half dozen are the most notable in applied sciences such as the life sciences and nuclear power, as detailed below. Mentions of radioiodine in health care contexts refer more often to iodine-131 than to other isotopes.
The radioisotopes were separated from neutron-irradiated target elements using remotely controlled robotic arms in heavily shielded hot cells in the nearby Radiochemical Engineering Development ...
Natural radioisotopes [ edit ] Many years ago radium-226 and radon-222 were used as gamma-ray sources for industrial radiography : for instance, a radon-222 source was used to examine the mechanisms inside an unexploded V-1 flying bomb , while some of the early Bathyspheres could be examined using radium-226 to check for cracks.
Radiochemistry also includes the study of the behaviour of radioisotopes in the environment; for instance, a forest or grass fire can make radioisotopes mobile again. [5] In these experiments, fires were started in the exclusion zone around Chernobyl and the radioactivity in the air downwind was measured.
Thirteen radioisotopes have been characterized; the most stable are 15 O with half-life 122.266(43) s and 14 O with half-life 70.621(11) s. All remaining radioisotopes have half-lives less than 27 s and most have half-lives less than 0.1 s. The four heaviest known isotopes (up to 28 O