A<unk> , radiotracer, or<unk>  label, is a chemical compound in which one or more atoms have been replaced by a radionuclide so by virtue of its<unk>  decay it can be used to explore the mechanism of chemical reactions by tracing the path that the radioisotope follows from reactants to products. Radiolabeling or radiotracing is thus the<unk>  form of isotopic labeling. In biological contexts, use of radioisotope<unk> s are sometimes called radioisotope feeding experiments. Radioisotopes of hydrogen, carbon, phosphorus, sulfur, and iodine have been used extensively to<unk> the path of biochemical reactions. A<unk>  can also be used to track the distribution of a substance within a natural system such as a cell or tissue, or as a flow<unk>  to track fluid flow.<unk> s are also used to determine the location of fractures created by hydraulic fracturing in natural gas production.<unk> s form the basis of a variety of imaging systems, such as, PET scans, SPECT scans and technetium scans. Radiocarbon dating uses the naturally occurring carbon-14 isotope as an isotopic label.
Radioactive tracer
Radiocontrast agent
Immunoconjugate
Magnetic-targeted carrier
Contrast agent
Idiotopes
PET radiotracer
Bicarbonate buffer system