title: Determination of radionuclides and radiochemical impurities produced by in-house cyclotron irradiation and subsequent radiosynthesis of PET tracers.
abstract: 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. Five11C-,15O-, or18F-labeled tracers produced from gaseous materials via chemical reactions had no radionuclidic impurities, whereas18F-FDG,18F-NaF, and13N-NH3produced from aqueous materials had several γ-emitters as well as impure positron emitters.15O-Labeled CO2, O2, and CO had a radionuclidic impurity13N-N2(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 for15O-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.
authors.affiliation: Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan. kiichiishiwata@gmail.com.|Institute of Cyclotron and Drug Discovery Research, Southern TOHOKU Research Institute for Neuroscience, 7-115 Yatsuyamada, Koriyama, 963-8052, Japan. kiichiishiwata@gmail.com.|Department of Biofunctional Imaging, Fukushima Medical University, Fukushima, Japan. kiichiishiwata@gmail.com.
authors.forename: Kiichi
authors.identifier: http://orcid.org/0000-0001-5773-7992
authors.initials: K
authors.lastname: Ishiwata
authors.affiliation: Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Kunpei
authors.initials: K
authors.lastname: Hayashi
authors.affiliation: Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Masanari
authors.initials: M
authors.lastname: Sakai
authors.affiliation: Production Technology Development Department, FUJIFILM RI Pharma, Sammu, Japan.
authors.forename: Sugio
authors.initials: S
authors.lastname: Kawauchi
authors.affiliation: Production Technology Development Department, FUJIFILM RI Pharma, Sammu, Japan.
authors.forename: Hideaki
authors.initials: H
authors.lastname: Hasegawa
authors.affiliation: Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Toyohara
mesh_terms: D017357:Cyclotrons; D005720:Gamma Rays; D006207:Half-Life; D049268:Positron-Emission Tomography; D011786:Quality Control; D011849:Radioactive Tracers; D011854:Radiochemistry / Q000295:instrumentation*; D011868:Radioisotopes / Q000737:chemistry*; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D011849:Radioactive Tracers; D011868:Radioisotopes; D019275:Radiopharmaceuticals
keywords: PET tracers; Quality control; Radiochemicals; Radionuclides