Internal radiotherapy techniques using radiolanthanide praseodymium-142: a review of production routes, brachytherapy, unsealed source therapy

Radionuclides of rare earth elements are gaining importance as emerging therapeutic agents in nuclear medicine. beta(-)-particle emitter Pr-142 [T-1/2 = 19.12 h, E-beta(-) = 2.162 MeV (96.3%), E gamma = 1575 keV (3.7%)] is one of the praseodymium-141 (100% abundant) radioisotopes. Production routes and therapy aspects of Pr-142 will be reviewed in this paper. However, Pr-142 produces via Pr-141(n, gamma)Pr-142 reaction by irradiation in a low-fluence reactor; Pr-142 cyclotron produced, could be achievable. Pr-142 due to its high beta(-)-emission and low specific gamma gamma-emission could not only be a therapeutic radionuclide, but also a suitable radionuclide in order for biodistribution studies. Internal radiotherapy using Pr-142 can be classified into two sub-categories: (1) unsealed source therapy (UST), (2) brachytherapy. UST via Pr-142-HA and Pr-142-DTPA in order for radiosynovectomy have been proposed. In addition, Pr-142 Glass seeds and Pr-142 microspheres have been utilized for interstitial brachytherapy of prostate cancer and intraarterial brachytherapy of arteriovenous malformation, respectively.