New developments in the production of theranostic pairs of radionuclides

A brief historical background of the development of the theranostic approach in nuclear medicine is given and seven theranostic pairs of radionuclides, namely Sc-44g/Sc-47, Cu-64/Cu-67, Sr-83/Sr-89, Y-86/Y-90, I-124/I-131, Tb-152/Tb-161 and Tb-152/Tb-149, are considered. The first six pairs consist of a positron and a (-)-emitter whereas the seventh pair consists of a positron and an -particle emitter. The decay properties of all those radionuclides are briefly mentioned and their production methodologies are discussed. The positron emitters Cu-64, Y-86 and I-124 are commonly produced in sufficient quantities via the (p,n) reaction on the respective highly enriched target isotope. A clinical scale production of the positron emitter Sc-44g has been achieved via the generator route as well as via the (p,n) reaction, but further development work is necessary. The positron emitters Sr-83 and Tb-152 are under development. Among the therapeutic radionuclides, Sr-89, Y-90 and I-131 are commercially available and Tb-161 can also be produced in sufficient quantity at a nuclear reactor. Great efforts are presently underway to produce Sc-47 and Cu-67 via neutron, photon and charged particle induced reactions. The radionuclide Tb-149 is unique because it is an -particle emitter. The present method of production of Tb-152 and Tb-149 involves the use of the spallation process in combination with an on-line mass separator. The role of some emerging irradiation facilities in the production of special radionuclides is discussed.