10 Things You Didnât Know About Chronic Fatigue Syndrome. Chronic Fatigue Syndrome (CFS) is undeniably complicated in every conceivable way. The disorder has been around for decades, but the medical community has yet to assemble a clear picture of it. The condition is characterized by extreme fatigue that canât be explained by any underlying medical condition.
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is an atom that has excess nuclear energy, making it unstable.
1. radioisotope-a radioactive isotope of an element; produced either naturally or artificially. tracer - (radiology) any radioactive isotope introduced into the body to study metabolism or other biological processes.isotope-one of two or more atoms with the same atomic number but with different numbers of neutrons.. radioisotope-a radioactive isotope of an element; produced either naturally or artificially. tracer - (radiology) any radioactive isotope introduced into the body to study metabolism or other biological processes.