The name technetium was derived by the scientist Mendeleyev from the Greek word technetos, meaning “artificial.” Technetium-99m was discovered in 1937 by Perrier and Segre in a sample of naturally occurring 98Mo irradiated by neutrons and deuterons. The first generator as a source for Tc-99m was introduced in 1957 at the Brookhaven National laboratory, and the first commercially available 99Mo-99mTc generator was made available in 1965. Use of Tc-99m really revolutionized nuclear medicine procedures, particularly with the modern gamma cameras coupled to advanced electronics and computing systems. This revolution was not completed until 1970, when the stannous ion reduction method of 99mTc-diethylenetriaminepentaacetate (DTPA) production as an “instant kit” was described, that simple and convenient “shake-and-bake” preparations for a large number of 99mTc-labeled radiopharmaceuticals were possible.