Effective production of 65Zn with a PET cyclotron

Cyclotrons dedicated to the production of PET radiopharmaceuticals for clinical use can be a resource also for research in other fields of science. In the present study we assessed the feasibility of 65Zn production via the 65Cu(p,n)65Zn reaction using a 16.5 MeV GE-PETtrace biomedical cyclotron. The radioisotope 65Zn (t1/2=244.26z d; decay mode: EC 98.3%, β+ 1.7%) has a wide range of applications, especially in botany and agriculture; its long half life allows storage and delivery to research centers without a cyclotron on site. Natural copper foils (thickness: 100 μm; purity: >99.9%) were irradiated in a solid target station developed in our institution. The EXFOR and IAEA cross sections databases were carefully studied to optimize the irradiation setup in order to maximize the yield of the radionuclide of interest and minimize the production of isotopic impurities. We performed production runs at 20 μA for 30 min. Activity was measured using a calibrated HPGe gamma ray detector and an ionization chamber radionuclide activity meter. These measures showed the presence of two main contaminants: 63Zn (t1/2=38.47 min) and 64Cu (t1/2=12.7 h); we produced 65Zn with a saturation yield of (1.06±0.07) GBq/μA (Ep=12.65→10.48 MeV). The irradiated target was dissolved in 1 ml of 6 N HNO3 at the temperature of 90 °C and then purified through anion exchange chromatography with BIO RAD AG 1×8 resin. The radionuclidic purity of the final solution of 65Zn in HCl 0.005 N, expressed in activity, resulted superior to (99.921±0.003) %. - Highlights: ► We showed the feasibility of the production of 65Zn(t1/2=244.26 d; decay mode: EC 98.3%, β+ 1.7%) via the 65Cu(p,n)65Zn reaction using a 16.5 MeV cyclotron. ► Natural Copper foils (thickness: 100 μm) were irradiated at 20 μA for 30 min, dissolved in 6 M HNO3 at 90 °C and purified through BIO RAD AG 1×8 resin. ► 65Zn saturation yield was (28.6±1.4) mCi/μA. ► Radionuclidic purity of the final solution of 65Zn in HCl 0.005 M is >99.986 %.