Radioisotopes are produced either with cyclotrons or with research nuclear reactors.

Production with nuclear reactors

Neutrons-rich radioisotopes are generally produced in research reactors. Fortunately, this is the case for the majority of medical radioisotopes (technetium-99m, iodine-131, holmium-166, lutecium-177, etc.) Reactors produce them in greater quantities, at a lower cost than cyclotrons. They ensure the production of many gamma emitters and all radionuclides used in therapy

Production with accelerators

Neutron-deficient radioisotopes are typically produced via charged-particle reactions in accelerators. (fluor-18, thallium-201, iodine-123, gallium-67, etc.) Additionally, they produce high specific activity products, with fewer radio-isotopic impurities by narrowing the irradiation energy window or through better chemical/physical separation techniques. However, their production yield is generally lower compared to reactors, and half-lives much shorter.