title: [Evaluation of Radio-activated Compounds Produced in the Walls and Adjacent Areas of a Small Medical Cyclotron].
abstract: According to the (18)O(p, n) (18)F reaction, fast neutrons produced in the target will cause residual radioactivity in a cyclotron itself and in the concrete walls mainly after thermalization of neutrons.As exploratory work prior to decommissioning of a medical cyclotron facility, surface and core samples of the facility's concrete walls were collected after confirming the external radiation was at a low level based on hollow ionization chamber-type survey meter and glass dosimeter measurements. The residual radioactivity in these samples was measured by gamma-spectrometry. Residual radioactivity was detected in all of the components of the cyclotron. In the concrete, eight residual radioactive nuclides were identified. However, radioactivity concentrations of these radionuclides were less than that of (40)K which may exist generally in a natural environment. A clearance level for radioactive solid waste has not been defined nor implemented at present in Japan, and reliable evaluation will be required to minimize radioactive waste at the time of decommissioning. The present results provide basic data for establishment of regulatory guidelines for decommissioning of medical cyclotrons.
authors: Department of Nuclear Medicine Technology, Gunma Prefectural College of Health Sciences.
authors: Kyoko
authors: K
authors: Saito
authors: Yasuyuki
authors: Y
authors: Takahashi
authors: Ichiro
authors: I
authors: Yamaguchi
authors: Ken-Ichi
authors: K
authors: Kimura
authors: Takao
authors: T
authors: Kanzaki
authors: Hirotaka
authors: H
authors: Shimada
authors: Hidenori
authors: H
authors: Otake
authors: Noboru
authors: N
authors: Oriuchi
authors: Keigo
authors: K
authors: Endo
mesh_terms: D017357:Cyclotrons; D009502:Neutrons; D011850:Radioactive Waste; D011851:Radioactivity; D011868:Radioisotopes; D013051:Spectrometry, Gamma
chemical_list: D011850:Radioactive Waste; D011868:Radioisotopes