Cyclotron production of 43Sc and 44gSc from enriched 42CaO, 43CaO, and 44CaO targets

Abstract

Introduction:43Sc and 44gSc are both positron-emitting radioisotopes of scandium with suitable half-lives and favorable positron energies for clinical positron emission tomography (PET) imaging. Irradiation of isotopically enriched calcium targets has higher cross sections compared to titanium targets and higher radionuclidic purity and cross sections than natural calcium targets for reaction routes possible on small cyclotrons capable of accelerating protons and deuterons.Methods: In this work, we investigate the following production routes via proton and deuteron bombardment on CaCO3 and CaO target materials: 42Ca(d,n)43Sc, 43Ca(p,n)43Sc, 43Ca(d,n)44gSc, 44Ca(p,n)44gSc, and 44Ca(p,2n)43Sc. Radiochemical isolation of the produced radioscandium was performed with extraction chromatography using branched DGA resin and apparent molar activity was measured with the chelator DOTA. The imaging performance of 43Sc and 44gSc was compared with 18F, 68Ga, and 64Cu on two clinical PET/CT scanners.Discussion: The results of this work demonstrate that proton and deuteron bombardment of isotopically enriched CaO targets produce high yield and high radionuclidic purity 43Sc and 44gSc. Laboratory capabilities, circumstances, and budgets are likely to dictate which reaction route and radioisotope of scandium is chosen.

De Novo Approaches to the Solid-Phase Separation of Titanium(IV) and Scandium(III): Translating Speciation Data to Selective On-Bead Chelation toward Applications in Nuclear Medicine

“…The production of 45 Ti and 44 Sc has been described previously. − Briefly, for 45 Ti, metal disks of nat Sc (9.5 mm diameter and 0.24 mm thickness) were spot-welded to tantalum backing coins (22 mm diameter and 1 mm thickness) and introduced to the proton beam of the University of Wisconsin’s General Electric PETtrace cyclotron using the GE Solid Target Platform, degraded to 11.8 MeV by passing through a 0.5 mm aluminum foil. After irradiation, activated nat Sc containing 45 Ti was dissolved in 5 mL of 6 M HCl, diluted to 15 mL with 18 MΩ-cm H 2 O, and loaded onto a preequilibrated ZR-resin (Triskem, France, preconditioned with 10 mL H 2 O and 2-5 mL 2M HCl) column.…”

Towards Clinical Development of Scandium Radioisotope Complexes for Use in Nuclear Medicine: Encouraging Prospects with the Chelator 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic Acid (DOTA) and Its Analogues

“…Several studies have described nuclear reactions under different conditions for the production of Sc-43 and Sc-44 from calcium and titanium, with different outcomes in each case, in terms of the yields and purities of the various radionuclides produced [ 43 , 58 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 ]. These scandium isotopes can be produced via multiple routes.…”

“…In this context, many studies have been reported for the nuclear reactions under different conditions for production of Sc-47, exhibiting different results in terms of yields and radionuclide purities ( Table 2 ) [ 43 , 59 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 ]. In contrast to Sc-43 and Sc-44, the production of Sc-47 can proceed by using high-energy proton irradiation of titanium [ 104 ], calcium [ 105 , 106 ], and vanadium targets [ 100 , 107 , 108 , 109 ].…”

“…In general, many separation methods have been reported in the literature for scandium isotopes and each of them is closely related to the type of the original target material/source, as described extensively elsewhere [ 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 ]. Similarly, different recovery yields, ranging from 45–98%, were reported for various systems, corresponding to the methods developed to allow separation of scandium isotopes from the target material [ 59 , 66 , 70 , 71 , 75 , 78 , 84 , 89 , 92 , ...…”