Production and separation of ''non-standard'' PET nuclides at a large cyclotron facility: the experiences at the Paul Scherrer Institute in Switzerland.

Radioimmuno-positron emission tomography (PET) combined with radioimmunotherapy is attractive to assess tumor targeting and quantitate the radiation dose to tumor and normal tissues. For this purpose, PET radionuclides with adequate physical half-lives matching those of the targeting molecule (e.g. antibodies) are preferable. Copper-64 (T 1/2 =12.7 h, E β + max =653 keV) and Zirconium-89 (T 1/2 =78.4 d, E β + max =901 keV) are attractive isotopes for this purpose. The 72 MeV cyclotron at the Paul Scherrer Institute provides the infrastructure for the production of a wide variety of radionuclides for diagnostic and therapeutic purposes. 64 Cu and 89 Zr are currently evaluated at the Center for Radiopharmaceutical Science (CRS) of the Paul Scherrer Institute (PSI) in combination with the L1 cam targeting antibody chCE7 and various protein formats thereof. A second focus of the CRS is the radiolabeling of small, tumor targeting molecules with technetium. The PET isotope 94m Tc offers potential alternative to its widely used 99m Tc SPECT counterpart. In this report, the development, optimization and pitfalls of 64 Cu, 89 Zr and 94m Tc production/separation are reported and discussed.