Production of 230U/226Th for Targeted Alpha Therapy via Proton Irradiation of 231Pa

Abstract

230U and its daughter nuclide 226Th are novel therapeutic nuclides for application in targeted r-therapy of cancer. We have investigated the feasibility of producing 230U/226Th via proton irradiation of 231Pa according to the reaction 231Pa(p,2n)230U. The experimental excitation function for this reaction is reported for the first time. Cross sections were measured using thin targets of 231Pa prepared by electrodeposition and 230U yields were analyzed using r-spectrometry. Beam parameters (energy and intensity) were determined both by calculation using a mathematical model based on measured beam orbits and beam current integrator and by parallel monitor reactions on copper foils using highresolution ¿-spectrometry and IAEA recommended cross-section data. The measured cross sections are in good agreement with model calculations using the EMPIRE-II code and are sufficiently high for the production of 230U/226Th in clinically relevant amounts. A highly effective separation process was developed to isolate clinical grade 230U from irradiated protactinium oxide targets. Product purity was assessed using r- and ¿-spectrometry as well as ICPMS.