State of the Art in Cyclotrons for Radionuclide Production in Biomedicine

Cyclotrons are one of the most important sources of radionuclides used in biomedical applications. The production of important radionuclides used in single-photon emission tomography techniques such as ¹²³I, ⁶⁷Ga, ²⁰¹Tl, and ¹¹¹In has been based for decades on cyclotrons, typically proton machines with an energy up to 30 MeV. The extraordinary growth of positron emission tomography (PET) has led to the development of new models and to the installation of numerous cyclotrons, typically accelerating protons in the energy range 10 to 20 MeV. These have been used for the production of the main PET radionuclides, namely, ¹¹C, ¹³N, ¹⁵O, and above all, ¹⁸F. Recently, their use has been extended to the production of radiometals, like ⁶⁸Ga, and even to the direct production of ^99mTc. Moreover, cyclotrons are a valuable tool for research and for the education of new scientists. This critical review presents the main manufacturers and briefly discusses the characteristics of the models they currently offer on the market.