Technetium is an element that doesn’t occur naturally on Earth and has to be synthesised. Commercially produced long-lived technetium isotopes are by-products of the fission of uranium 235 in nuclear reactors and extracted from nuclear fuel rods (Separation of uranium from technetium in recovery of spent nuclear fuel (1984)).
The Tc 99m metastable isotope has a number of important applications especially in nuclear medicine.
Tc 99m is produced from Mo 99 by neutron capture and the two species have to be separated chemically (Method For Separating Technetium 99 From Molybdenum 99 (1972)).
Tc 99m labelled complexes can be used in medical applications such as imaging the liver and bile duct (Neutral technetium 99-m complexes useful as radiodiagnostic agents.(1988)).
Tc 99m compounds have applications in marine antifouling, and in corrosion protection (Method For The Prevention Of Fouling And Corrosion Utilizing Technetium-99 (1982)).