⁴⁴Sc has favorable properties for cancer diagnosis using Positron Emission Tomography (PET) making it a promising candidate for application in nuclear medicine. The implementation of its production with existing compact medical cyclotrons would mean the next essential milestone in the development of this radionuclide. While the production and application of ⁴⁴Sc has been comprehensively investigated, the development of specific targetry and irradiation methods is of paramount importance. As a result, the target was optimized for the ⁴⁴Ca(p,n)⁴⁴Sc nuclear reaction using CaO instead of CaCO₃, ensuring decrease in target radioactive degassing during irradiation and increased radionuclidic yield. Irradiations were performed at the research cyclotron at the Paul Scherrer Institute (~11 MeV, 50 µA, 90 min) and the medical cyclotron at the University of Bern (~13 MeV, 10 µA, 240 min), with yields varying from 200 MBq to 16 GBq. The development of targetry, chemical separation as well as the practical issues and implications of irradiations, are analyzed and discussed. As a proof-of-concept study, the ⁴⁴Sc produced at the medical cyclotron was used for a preclinical study using a previously developed albumin-binding prostate-specific membrane antigen (PSMA) ligand. This work demonstrates the feasibility to produce ⁴⁴Sc with high yields and radionuclidic purity using a medical cyclotron, equipped with a commercial solid target station.

The favorable decay properties of 43Sc and 44Sc for PET make them promising candidates for future applications in nuclear medicine. An advantage 43Sc (T1/2 = 3.89 h, Eβ+ av = 476 keV [88%]) exhibits over 44Sc, however, is the absence of co-emitted high energy γ-rays. While the production and application of 44Sc has been comprehensively discussed, research concerning 43Sc is still in its infancy. This study aimed at developing two different production routes for 43Sc, based on proton irradiation of enriched 46Ti and 43Ca target material. 43Sc was produced via the 46Ti(p,α)43Sc and 43Ca(p,n)43Sc nuclear reactions, yielding activities of up to 225 MBq and 480 MBq, respectively. 43Sc was chemically separated from enriched metallic 46Ti (97.0%) and 43CaCO3 (57.9%) targets, using extraction chromatography. In both cases, ~90% of the final activity was eluted in a small volume of 700 μL, thereby, making it suitable for direct radiolabeling. The prepared products were of high radionuclidic purity, i.e. 98.2% 43Sc were achieved from the irradiation of 46Ti, whereas the product isolated from irradiated 43Ca consisted of 66.2% 43Sc and 33.3% 44Sc. A PET phantom study performed with 43Sc, via both nuclear reactions, revealed slightly improved resolution over 44Sc. In order to assess the chemical purity of the separated 43Sc, radiolabeling experiments were performed with DOTANOC, attaining specific activities of 5–8 MBq/nmol, respectively, with a radiochemical yield of >96%. It was determined that higher 43Sc activities were accessible via the 43Ca production route, with a comparatively less complex target preparation and separation procedure. The product isolated from irradiated 46Ti, however, revealed purer 43Sc with minor radionuclidic impurities. Based on the results obtained herein, the 43Ca route features some advantages (such as higher yields and direct usage of the purchased target material) over the 46Ti path when aiming at 43Sc production on a routine basis.

The new Bern cyclotron laboratory aims at industrial radioisotope production for PET diagnostics and multidisciplinary research by means of a specifically conceived beam transfer line, terminated in a separate bunker. In this framework, an innovative beam monitor detector based on doped silica and optical fibres has been designed, constructed, and tested. Scintillation light produced by Ce and Sb doped silica fibres moving across the beam is measured, giving information on beam position, shape, and intensity. The doped fibres are coupled to commercial optical fibres, allowing the read-out of the signal far away from the radiation source. This general-purpose device can be easily adapted for any accelerator used in medical applications and is suitable either for low currents used in hadrontherapy or for currents up to a few μA for radioisotope production, as well as for both pulsed and continuous beams.

¹⁵⁵Tb [t_1/2 = 5.32 d, E_γ = 87 keV (32%); 105 keV (25%) (IAEA, 2021)] is a novel promising radionuclide for theranostic applications in nuclear medicine. Its physical properties make it suitable for single photon emission computed tomography (SPECT) imaging, while its chemistry allows it to be used as a diagnostic partner for therapeutic radiolanthanides or pseudo-radiolanthanides, such as ¹⁷⁷Lu and ⁹⁰Y. Moreover, ¹⁵⁵Tb could be used as a precise diagnostic match for the β^--emitter ¹⁶¹Tb, opening doors for the true theranostics concept. The availability of ¹⁵⁵Tb in quantity and quality suitable for medical applications is an open issue and its production with medical cyclotrons via the ¹⁵⁵Gd(p,n)¹⁵⁵Tb and ¹⁵⁶Gd(p,2n)¹⁵⁵Tb nuclear reactions represents a possible but challenging solution. For this purpose, an accurate knowledge of the production cross sections is mandatory. In this paper, we report on the measurement of the production cross sections of ¹⁵⁵Tb and other terbium radionuclides formed by proton irradiation of ^natGd₂O₃, ¹⁵⁵Gd₂O₃ and ¹⁵⁶Gd₂O₃ enriched targets, performed at the Bern University Hospital cyclotron laboratory. On the basis of the obtained results, the production yield and purity were calculated to assess the optimal irradiation conditions. The results of several production tests are also presented.