title: Radiologic assessment of a self-shield with boron-containing water for a compact medical cyclotron.
abstract: The cyclotron at our hospital has a self-shield of boron-containing water. The amount of induced radioactivity in the boron-containing water shield of a compact medical cyclotron has not yet been reported. In this study, we measured the photon and neutron dose rates outside the self-shield during cyclotron operation. We estimated the induced radioactivities of the boron-containing water used for the self-shield and then measured them. We estimated the activation of concrete outside the self-shield in the cyclotron laboratory. The thermal neutron flux during cyclotron operation was estimated to be 4.72 × 10(2) cm(-2) s(-1), and the activation of concrete in a cyclotron laboratory was about three orders of magnitude lower than the clearance level of RS-G-1.7 (IAEA). The activity concentration of the boron-containing water did not exceed the concentration limit for radioactive isotopes in drainage in Japan and the exemption level for Basic Safety Standards. Consequently, the boron-containing water is treatable as non-radioactive waste. Neutrons were effectively shielded by the self-shield during cyclotron operation.
authors.affiliation: MI Clinic, Shoji 1-12-13, Toyonaka, Osaka 560-0004, Japan. horitsugi@jinsen-pet.jp
authors.forename: Genki
authors.initials: G
authors.lastname: Horitsugi
authors.forename: Toshioh
authors.initials: T
authors.lastname: Fujibuchi
authors.forename: Ichiro
authors.initials: I
authors.lastname: Yamaguchi
authors.forename: Akihisa
authors.initials: A
authors.lastname: Eto
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Iwamoto
authors.forename: Hiromi
authors.initials: H
authors.lastname: Hashimoto
authors.forename: Seiki
authors.initials: S
authors.lastname: Hamada
authors.forename: Satoshi
authors.initials: S
authors.lastname: Obara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Watanabe
authors.forename: Jun
authors.initials: J
authors.lastname: Hatazawa
mesh_terms: D001895:Boron; D017357:Cyclotrons; D009502:Neutrons; D017785:Photons; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation*; D011851:Radioactivity; D013997:Time Factors; D014867:Water
chemical_list: D014867:Water; D001895:Boron