188W/188Re generator system and its therapeutic applicacions

The Re-188 radioisotope represents a useful radioisotope for the preparation of radiopharmaceuticals for therapeutic applications, particularly because of its favorable nuclear properties. The nuclide decay pattern is through the emission of a principle beta particle having 2.12MeV maximum energy, which is enough to penetrate and destroy abnormal tissues, and principle gamma rays (E gamma = 155 keV), which can efficiently be used for imaging and calculations of radiation dose. Re-188 may be conveniently produced by W-188/Re-188 generator systems. The challenges related to the double neutron capture reaction route to provide only modest yield of the parent (188W) radionuclide indeed have been one of the major issues about the use of Re-188 in nuclearmedicine. Since the specific activity of W-188 used in the generator is relatively low (<185GBq/g), the eluted (ReO4-)-Re-188 can have a low radioactive concentration, often ineffective for radiopharmaceutical preparation. However, several efficient postelution concentration techniques have been developed, which yield clinically useful (ReO4-)-Re-188 solutions. This review summarizes the technologies developed for the preparation of W-188/Re-188 generators, postelution concentration of the Re-188 perrhenate eluate, and a brief discussion of new chemical strategies available for the very high yield preparation of Re-188 radiopharmaceuticals.