[en] The first small cyclotrons were installed for commercial production of radioisotopes at New England Nuclear Corporation, Billerica, Massachusetts, and at Medi-Physics, Emeryville, California. Both machines were Cyclotron Corporation Cs-22 multiple particle, fixed energy cyclotrons. In the ten years that followed, the total number of commercial radioisotope producing small accelerators has grown to ten, with four more projected for 1981. The beam energy requirement for the first accelerators was modest; 22 MeV protons, 12 MeV deuterons, 24 MeV He-4, and 31 MeV He-3; and commercial radioisotope production for nuclear medicine utilized all four particles. The first product available from cyclotron production was fluorine-18 from the ¹⁶O(³He, p)¹⁸F reaction. Injected intravenously as no-carrier-added Na¹⁸F, the radionuclide quickly concentrated in bone, providing the nuclear medicine physician with diagnostic information on skeletal abnormalities including metastatic bone disease