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

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. Sc-47 is a beta(-) emitter that forms a theranostic pair together with one of the beta(+) emitters Sc-43 or Sc-44. It can be produced at a medical cyclotron by proton bombardment of an enriched calcium oxide target. The parasite production of Sc-48 undermines the Sc-47 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 Ca-44(p,n)Sc-44m,Ca-48 (p,n)Sc-48, Ca-48(p,2n)Sc-47 and Ca-48(p,pn)Ca-47 using (CaCO3)-Ca-nat 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.