Theoretical estimation of 64Cu production with neutrons emitted during 18F production with a 30 MeV medical cyclotron

Abstract

PurposeThis work presents the theoretical estimation of a combined production of 18F and 64Cu isotopes for PET applications. 64Cu production is induced in a secondary target by neutrons emitted during a routine 18F production with a 30MeV cyclotron: protons are used to produce 18F by means of the 18O(p,n)18F reaction on a [18O]-H2O target (primary target) and the emitted neutrons are used to produce 64Cu by means of the 64Zn(n,p)64Cu reaction on enriched zinc target (secondary target). MethodsMonte Carlo simulations were carried out using Monte Carlo N Particle eXtended (MCNPX) code to evaluate flux and energy spectra of neutrons produced in the primary (Be+[18O]-H2O) target by protons and the attenuation of neutron flux in the secondary target. 64Cu yield was estimated using an analytical approach based on both TENDL-2015 data library and experimental data selected from EXFOR database. ResultsTheoretical evaluations indicate that about 3.8 MBq/μA of 64Cu can be obtained as a secondary, ‘side’ production with a 30MeV cyclotron, for 2h of irradiation of a proper designed zinc target. Irradiating for 2h with a proton current of 120 μA, a yield of about 457 MBq is expected. Moreover, the most relevant contaminants result to be 63,65Zn, which can be chemically separated from 64Cu contrarily to what happens with proton irradiation of an enriched 64Ni target, which provides 64Cu mixed to other copper isotopes as contaminants. ConclusionsThe theoretical study discussed in this paper evaluates the potential of the combined production of 18F and 64Cu for medical purposes, irradiating a properly designed target with 30MeV protons. Interesting yields of 64Cu are obtainable and the estimation of contaminants in the irradiated zinc target is discussed.