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44Sc is a β + -emitter which has been extensively studied for nuclear medicine applications. Its promising decay characteristics [t 1 / 2 = 3.97 h, E β + = 632 keV (94.3%), E γ = 1157 keV (99.9%); 1499 keV (0.91%)] make it highly attractive for clinical PET imaging, offering an alternative to the widely used 68Ga [t 1 / 2 = 67.7 min, E β + = 836 keV (87.7%)]. Notably, its nearly fourfold longer half-life opens avenues for applications with biomolecules having extended biological half-lives and enables the centralized distribution of 44Sc radiopharmaceuticals. An additional advantage of employing 44Sc as a diagnostic radioisotope lies in its counterpart, the β − -emitter 47Sc, which is currently under investigation for targeted radiotherapy. Together, they form an ideal theranostic pair, providing a comprehensive solution for both diagnostic imaging and therapeutic applications in nuclear medicine. At the Bern medical cyclotron, a study to optimize the production of scandium radioisotopes is currently ongoing. In this context, proton irradiation of titanium targets has been investigated, exploiting the reactions 47Ti(p, α)44Sc and 50Ti(p, α)47Sc. This approach enables the production of Sc radioisotopes within a single PET medical cyclotron facility, employing identical chemical procedures for target preparation and post-irradiation processing. In this paper, we report on cross-section measurements of the 47Ti(p, α)44Sc nuclear reaction using 95.7% enriched 47TiO 2 targets. On the basis of the obtained results, the production yield and purity were calculated to assess the optimal irradiation conditions. Production tests were performed to confirm these findings. • Measurement of the 47Ti(p, α)44Sc nuclear cross sections by irradiating 47Ti targets. • Measurements performed using an 18 MeV medical cyclotron and a beam transfer line. • Study of the thick target production yield and purity. • Production tests performed using a custom target station. • Suitable alternative route to produce 44Sc with a PET medical cyclotron. [ABSTRACT FROM AUTHOR]

155Tb is one of the most interesting radionuclides for theranostic applications. It is suitable for SPECT imaging and it can be used as a true diagnostic partner of the therapeutic 149Tb and 161Tb. Its production by proton irradiation using enriched 155Gd and 156Gd oxide targets is currently being investigated and represents a promising solution. To achieve the level of radionuclidic purity required in the clinical setting, the co-production of Tb impurities has to be minimized. For this purpose, an accurate knowledge of the cross sections of the nuclear reactions involved is of paramount importance. In this paper, we report on the assessment of cross sections of the reactions 154Gd(p,xn) 153 , 154 , 154 m 1 , 154 m 2 Tb, 155Gd(p,xn) 154 , 154 m 1 , 154 m 2 , 155 Tb, 156Gd(p,xn) 155 , 156 Tb and 157Gd(p,2n)156Tb derived with a specific data analysis procedure developed by our group. This method allows to disentangle the nuclear contributions from the production cross section by inverting linear systems of equations and it requires the measurement of the cross sections from as many materials as the reactions involved in the production of the radionuclide under study. For this purpose, the experimental data previously measured by our group at the Bern medical cyclotron by irradiating natural Gd 2 O 3 , enriched 155Gd 2 O 3 and enriched 156Gd 2 O 3 targets were used. For some of these nuclear reactions, cross sections were assessed for the first time. On the basis of our findings, production yield and purity can be calculated for any kind of isotopic composition of the enriched material. • Tb radioisotopes cross-section measurements by irradiating Gd targets. • Measurements performed using a beam transfer line and a 18 MeV medical PET cyclotron. • The nuclear cross sections of terbium radioisotopes were experimentally assessed. • Method based on the inversion of a linear system of equations. [ABSTRACT FROM AUTHOR]

RadioNuclide Therapy (RNT) in nuclear medicine is a cancer treatment based on the administration of radioactive substances that specifically target cancer cells in the patient. These radiopharmaceuticals consist of tumor-targeting vectors labeled with β − , α , or Auger electron-emitting radionuclides. In this framework, 67Cu is receiving increasing interest as it provides β − -particles accompanied by low-energy γ radiation. The latter allows to perform Single Photon Emission Tomography (SPECT) imaging for detecting the radiotracer distribution for an optimized treatment plan and follow-up. Furthermore, 67Cu could be used as therapeutic partner of the β + -emitters 61Cu and 64Cu, both currently under study for Positron Emission Tomography (PET) imaging, paving the way to the concept of theranostics. The major barrier to a wider use of 67Cu-based radiopharmaceutical is its lack of availability in quantities and qualities suitable for clinical applications. A possible but challenging solution is the proton irradiation of enriched 70Zn targets, using medical cyclotrons equipped with a solid target station. This route was investigated at the Bern medical cyclotron, where an 18 MeV cyclotron is in operation together with a solid target station and a 6-m-long beam transfer line. The cross section of the involved nuclear reactions were accurately measured to optimize the production yield and the radionuclidic purity. Several production tests were performed to confirm the obtained results. • 67Cu cross-section measurements by irradiating 70Zn targets. • Measurements performed using an 18 MeV medical cyclotron and a beam transport line. • Study of production yield and purity. • Production tests performed with solid targets. • 18 MeV cyclotrons are suitable to produce 67Cu for RNT in nuclear medicine. [ABSTRACT FROM AUTHOR]

165Er is a pure Auger-electron emitter with promising characteristics for therapeutic applications in nuclear medicine. The short penetration path and high Linear Energy Transfer (LET) of the emitted Auger electrons make 165Er particularly suitable for treating small tumor metastases. Several production methods based on the irradiation with charged particles of Er and Ho targets can be found in the literature. In this paper, we report on the study of 165Er indirect production performed via the 166Er(p,2n)165Tm → 165Er reaction at the 18 MeV Bern medical cyclotron. Despite the use of highly enriched 166Er 2 O 3 targets, several Tm radioisotopes are produced during the irradiation, making the knowledge of the cross sections involved crucial. For this reason, a precise investigation of the cross sections of the relevant nuclear reactions in the energy range of interest was performed by irradiating Er 2 O 3 targets with different isotopic enrichment levels and using a method based on the inversion of a linear system of equations. For the reactions 164Er(p, γ)165Tm, 166Er(p,n)166Tm, 166Er(p, γ)167Tm, 167Er(p,3n)165Tm, 167Er(p, γ)168Tm, 168Er(p,2n)167Tm and 170Er(p,3n)168Tm, the nuclear cross section was measured for the first time. From the results obtained, the production yield and purity of the parent radioisotope 165Tm were calculated to assess the optimal irradiation conditions. Several production tests with solid targets were performed to confirm these findings. • Indirect production of the medically-relevant 165 Er. • Measurement of Tm radioisotope cross sections by irradiating Er oxide. • Measurements performed using an 18 MeV medical cyclotron and a beam transport line. • Method based on the inversion of a linear system of equations. • Study of the thick target yield and purity. [ABSTRACT FROM AUTHOR]