Actinium-225 and Bi have been used successfully in targeted alpha therapy (TAT) in preclinical and clinical research. This paper is a continuation of research activities aiming to expand the availability ofAc. The high-energy proton spallation reaction on natural thorium metal targets has been utilized to produce millicurie quantities of Ac. The results of sixteen irradiation experiments of thorium metal at beam energies between 78 and 192MeV are summarized in this work. Irradiations have been conducted at Brookhaven National Laboratory (BNL) and Los Alamos National Laboratory (LANL), while target dissolution and processing was carried out at Oak Ridge National Laboratory (ORNL). Excitation functions for actinium and thorium isotopes, as well as for some of the fission products, are presented. The cross sections for production ofAc range from 3.6 to 16.7mb in the incident proton energy range of 78-192MeV. Based on these data, production of curie quantities of Ac is possible by irradiating a 5.0gcmTh target for 10 days in either BNL or LANL proton irradiation facilities.

To advance the chelation chemistry of the elusive radium ion for targeted radionuclide therapy applications, we report its complexation thermodynamics with the macrocyclic chelators macropa and DOTA.

The alpha-emitters 225 Ac and 213 Bi are of great interest for alpha-radioimmunotherapy which uses radioisotopes attached to cancer-seeking antibodies to efficiently treat various types of cancers. Both radioisotopes are daughters of the long-lived 229 Th (t 1/2 = 7880y). 229 Th can be produced by proton irradiation of 232 Th and 230 Th, either directly or through production of isobars that beta-decay into 229 Th. To obtain excitation functions, 232 Th and 230 Th have been irradiated at the On-Line Test Facility at the Holifield Radioactive Ion Beam Facility at ORNL. Benchmark tests conducted with Cu and Ni foils show very good agreement with literature results. The experiments with thorium targets were focused on the production of 229 Pa and its daughter 225 Ac from both 232 Th and 230 Th. Differential cross-sections for production of 229 Pa and other Pa isotopes have been obtained.

A new method has been developed for the isolation of 223,224,225Ra, in high yield and purity, from a proton irradiated 232Th matrix. Herein we report an all-aqueous process using multiple solid-supported adsorption steps including a citrate chelation method developed to remove >99.9% of the barium contaminants by activity from the final radium product. A procedure involving the use of three columns in succession was developed, and the separation of 223,224,225Ra from the thorium matrix was obtained with an overall recovery yield of 91 ± 3%, average radiochemical purity of 99.9%, and production yields that correspond to physical yields based on previously measured excitation functions.