Radiolysis reduction in liquid solution targets for the production of 89Zr

N A Zacchia; D M Martinez; C Hoehr

doi:10.1016/j.apradiso.2019.06.037

Radiolysis reduction in liquid solution targets for the production of ⁸⁹Zr

Appl Radiat Isot. 2020 Jan:155:108791. doi: 10.1016/j.apradiso.2019.06.037. Epub 2019 Jun 29.

Authors

N A Zacchia¹, D M Martinez², C Hoehr³

Affiliations

¹ TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, Canada, V6T 2A3; Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC, Canada, V6T 1Z3. Electronic address: nzacchia@triumf.ca.
² Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC, Canada, V6T 1Z3.
³ TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, Canada, V6T 2A3.

PMID: 31756554
DOI: 10.1016/j.apradiso.2019.06.037

Abstract

Increased interest in radiometals for nuclear medicine and imaging can be hampered by radionuclide supply. ⁸⁹Zr for example, is a PET imaging nuclide for which no radionuclide generator exists. One method to produce ⁸⁹Zr involves irradiating aqueous solutions of yttrium nitrate salt on small medical cyclotrons. However, in irradiating these solutions the radiolysis of water can cause significant H₂ and O₂ gas buildup, which can eventually rupture a sealed target vessel. We examine the role of nitrate and nitrite in radiolysis. Here, we find that using copper-coated cadmium pellets to chemically reduce nitrate to nitrite in solution prior to irradiation can reduce in-target radiolysis by approximately 60% as compared to other published methods of radiolysis reduction, but only in acidic solutions. We hypothesize that during irradiation, nitrate is converted to nitrite, consuming free radicals which would otherwise be available to eliminate molecular gas species. Performing this conversion before irradiation may limit the consumption of these beneficial free radicals.

Keywords: Liquid target; Medical isotopes; PET; Radiometals; Radionuclides; Zr-89.