Gamma-ray measurements of the activated target components in a cyclotron used for positron emission tomography. (December 2020)

• Record Type: Journal Article
• Authors: Jurado Vargas, M.; Carbajo Chávez, J.C.; Sánchez Sánchez, R.; Sosa, C.
• Is Part Of: Radiation physics and chemistry. Volume 177(2020:Dec.)
• Publication Date: 2020-12
• Subjects: 18F -- FDG -- Medical cyclotron -- HAVAR™ -- Waste management -- Operational dosimetry; Radiation chemistry -- Periodicals; Radiometry -- Periodicals; Radiation -- Periodicals; Chimie sous rayonnement -- Périodiques; 539.2
• DOI: 10.1016/j.radphyschem.2020.109153
• Languages: English
• ISSNs: 0969-806X

Abstract

Abstract: The proton irradiation in a PET cyclotron produces radioactive by-products with high levels of activity in the target components, which are strongly dependent on the specific parameters used in the cyclotron facility. Because the target assembly parts must be replaced periodically, external exposure to operators must be assessed. In this work, high-resolution gamma-ray spectrometry was used to determine the activity levels for the specific radionuclides induced in the target components of a medical 9.6 MeV MINItrace cyclotron. The focus was on three target components, which are periodically replaced: Havar foil, Titanium foil and the Helicoflex seal located on the path of the proton beam just in front of the silver vessel containing the enriched water. Eight radionuclides were identified in the Havar foil: 54 Mn, 56 Co, 57 Co, 58 Co, 60 Co, 95 Tc, 109 Cd and 183 Re. In the titanium foil, the nuclides 46 Sc, 48 V, 51 Cr, 56 Co, 57 Co, and 75 Se were identified, while only 51 Cr, 58 Co, and 60 Co were detected in the Helicoflex seal. The total effective dose rates to which staff are exposed at the moment of replacing the target were calculated. The waste management for these target components was also considered, using the half-lives of the detected radionuclides in order to determine the time necessary for the activity levels in the target components to be below the exemption levels recommended by the IAEA. Highlights: Determination of activities for radionuclides induced in target components of a medical 9.6 MeV cyclotron. High-resolution gamma-ray spectrometry used to identify the radionuclides induced. Three target components periodically replaced in clyclotron were analysed: Havar foil, Titanium foil and Helicoflex seal. Total effective dose rates at which the staff are exposed were calculated. Waste management for these target components was also considered and discussed.