Cross-section measurement of 44mSc,47Sc, 48Sc and 47Ca for an optimized 47Sc production with an 18 MeV medical PET cyclotron.

ABSTRACT

Novel medical radioisotopes for both diagnostic and therapy are essential for the future development of personalized nuclear medicine. Among them, radiometals can be used to label both proteins and peptides and encompass promising theranostic pairs. The optimized supply of radiometals in quantity and quality for clinical applications represents a scientific and technological challenge. 47Sc is a ß- emitter that forms a theranostic pair together with one of the ß+ emitters 43Sc or 44Sc. It can be produced at a medical cyclotron by proton bombardment of an enriched calcium oxide target. The parasite production of 48Sc undermines the 47Sc purity, which strongly depends on the energy of protons impinging the target and on the thickness of the target material. For this purpose, an accurate knowledge of the production cross-sections is mandatory. In this paper, we report on the measurement of the cross-section of the reactions 44Ca(p,n)44 mSc,48Ca(p,n)48Sc, 48Ca(p,2n)47Sc and 48Ca(p,pn)47Ca using natCaCO3 targets performed at the Bern University Hospital cyclotron laboratory. On the basis of the obtained results and of the isotopic composition of commercially available enriched target materials, the thick target yields and the purity were calculated to assess the optimal irradiation conditions.