Accelerator-based photoproduction of promising beta-emitters 67Cu and 47Sc

Abstract

In this paper we discuss our experimental work in photoproducing two medically-useful radioisotopes ( 68 Zn(c,p) 67 Cu and 48 Ca(c,n) 47 Ca ? 47 Sc) using an electron linear accelerator. We further address the issues of production and separation of medical isotopes arising from photoneutron (c,n) and photoproton (c,p) reactions. While (c,n) reactions typically result in greater yields, separating product nuclides from the target is challenging since the chemical properties of both nuclides are identical. Although the yields of (c,p) reactions are typically lower than for (c,n), these proton-rich isotopes have the advantage that target and product nuclides belong to different chemical species allowing for more straightforward chemical separation. We conclude the paper by touching upon the dire necessity of experimentally revisiting a broad swath of photonuclear reactions in the 10-to 50-MeV regime. The very paucity of empirical cross-sectional data makes it altogether impossible to realistically predict accelerator-based photoproduction of many promising radiopharmaceuticals.

Radiometals for imaging and theranostics, current production, and future perspectives

“…The method of 47 Sc production using eLINACs has been proposed in the literature . The concept was studied, using the 48 Ti(γ,p) 47 Sc nuclear reaction, by Monte Carlo simulations, while preliminary experimental results using enriched 48 Ti were also reported .…”

“…93 The production of 47 Sc can be achieved via various nuclear reactions using a cyclotron, 94 reactor, 95 or electron linear accelerator (eLINAC). [96][97][98][99] The cyclotron production of 47 Sc via the 48 Ca(p,2n) 47 Sc nuclear reaction has been reported, with a proton energy range of 24 → 17 MeV regarded as optimal for this purpose. The radionuclidic purity using this route was determined to be only 85% to 87%, however.…”

“…However, similarly to the direct route, highly enriched targets are required and the large masses of target material are needed in order to produce the required radioactivity of 177 Lu, because of the low thermal neutron capture cross section and low production yield. The costeffectiveness of both production routes is difficult to 99.5% is around 20 USD/mg, but the mass of target material to produce equivalent radioactivity of 177 Lu is at the level of two to three orders of magnitude higher. Hence, recycling of 176 Yb is needed to keep the production cost reasonable.…”

Development of novel radionuclides for medical applications

“…In recent years, there has been an increasing interest in the utilization of electron linear accelerators for medical radionuclide production, and the reaction 68 Zn(γ,p) 67 Cu has been investigated in some detail . The yield is rather low, and the present day photon sources are not capable of delivering the radionuclide in the required quantity.…”

“…In recent years, there has been an increasing interest in the utilization of electron linear accelerators for medical radionuclide production, and the reaction 68 Zn(γ,p) 67 Cu has been investigated in some detail. 116,117 The yield is rather low, and the present day photon sources are not capable of delivering the radionuclide in the required quantity. However, with further intensification of technological efforts to develop high-intensity accelerators, it should be possible to produce 67 Cu in larger quantities.…”