Production of the PET radionuclide 61 Cu via the 62 Ni(p,2n) 61 Cu nuclear reaction

Abstract Background There are only a handful of true theranostic matched pairs, and in particular the theranostic radiocopper trio 61 Cu, 64 Cu and 67 Cu, for diagnosis and therapy respectively, is a very attractive candidate. In fact, the alternative of two imaging radionuclides with different half-lives is a clear advantage over other theranostic pairs, since it offers a better matching for the tracer biological and radionuclide physical half-lives. Due to the high availability of 64 Cu, its translation into the clinic is being successfully carried out, giving the example of the FDA approved radiopharmaceutical Detectnet (copper Cu 64 dotatate injection). However, a shorter-lived PET radionuclide such as 61 Cu may as well be beneficial. Results Proton irradiation of enriched 62 Ni electrodeposited targets with a compact cyclotron produced the desired radionuclide via the 62 Ni(p,2n) 61 Cu nuclear reaction, leading to 61 Cu activities of up to 20 GBq at end of bombardment and 8 GBq at end of purification. Furthermore, two purification methods are compared leading to comparable results regarding separation yield and product purity. Following the radiochemical separation, quality assessment of this product [ 61 Cu]CuCl 2 solution proved radionuclidic purities (RNP) over 99.6% and apparent molar activities (AMA) of 260 GBq/µmol with the 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (TETA) chelator, end of purification corrected. Conclusions In the current article a comprehensive novel production method for the PET radionuclide 61 Cu is presented, providing an alternative to the most popular production routes. Characterization of the [ 61 Cu]CuCl 2 product showed both high RNP as well as high AMA, proving that the produced activity presented high quality regarding radiolabeling up to 9 h after end of purification. Furthermore, production scalability could be easily achieved by increasing the irradiation time. Graphical abstract