Radioactive tracer such as a cell or tissue, or as a flow tracer to track fluid flow. Radioactive tracers are also used to determine the location of fractures created by hydraulic fracturing in natural gas production. Radioactive tracers 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. Isotopes of a chemical element differ only in the mass number. For example, the isotopes of hydrogen can be written as H, H and H, with the mass number at top left. When the
Pertechnetate is found in a Meckel's diverticulum with Meckel's scans. All technetium salts are mildy radioactive, but some of them have explored use of the element for its chemical properties. In these uses, its radioactivity is incidental, and generally the least radioactive (longest-lived) isotopes of Tc are used. In particular, Tc (half-life 211,000 years) is used in corrosion research, because it is the decay product of the easily obtained commercial Tc isotope, which is its nuclear isomer. In theory, the longest-lived technetium isotope, Tc (half-life 4.2 million years), would be the optimal isotope for this use. Solutions of technetate(VII) react with