1. Division of Biomedical Radiation Sciences, Box 535, S-751 21, Uppsala University, Uppsala, Sweden, Uppsala University PET-Centre, Uppsala University, Uppsala, Sweden, Department of Organic Chemistry, Uppsala University, Uppsala, Sweden, Nesmeyanov Institute of Organo-Element Compounds, Moscow, Russia, RRC “Kurchatov Institute”, Moscow, Russia, and Institute for Medical Radiobiology, Paul Scherrer Institut, Villigen, Switzerland