Determination of radionuclides and radiochemical impurities produced by in-house cyclotron irradiation and subsequent radiosynthesis of PET tracers

OBJECTIVE: To elucidate the radionuclides and radiochemical impurities included in radiosynthesis processes of positron emission tomography (PET) tracers. METHODS: Target materials and PET tracers were produced using a cyclotron/synthesis system from Sumitomo Heavy Industry. Positron and γ-ray emitting radionuclides were quantified by measuring radioactivity decay and using the high-purity Ge detector, respectively. Radiochemical species in gaseous and aqueous target materials were analyzed by gas and ion chromatography, respectively. RESULTS: Target materials had considerable levels of several positron emitters in addition to the positron of interest, and in the case of aqueous target materials extremely low levels of many γ-emitters. Five (11)C-, (15)O-, or (18)F-labeled tracers produced from gaseous materials via chemical reactions had no radionuclidic impurities, whereas (18)F-FDG, (18)F-NaF, and (13)N-NH(3) produced from aqueous materials had several γ-emitters as well as impure positron emitters. (15)O-Labeled CO(2), O(2), and CO had a radionuclidic impurity (13)N-N(2) (0.5–0.7 %). CONCLUSIONS: Target materials had several positron emitters other than the positron of interest, and extremely low level γ-emitters in the case of aqueous materials. PET tracers produced from gaseous materials except for (15)O-labeled gases had no impure radionuclides, whereas those derived from aqueous materials contained acceptable levels of impure positron emitters and extremely low levels of several γ-emitters. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s12149-016-1134-3) contains supplementary material, which is available to authorized users.