title: Effects of dose rate and energy level on fission neutron (252Cf) tumorigenesis in B6C3F1 mice.
abstract: The effects of the dose rate and the energy of fission neutrons using an iron block on tumorigenesis in B6C3F1 mice were examined. Six-week-old female animals were divided into 4 groups and exposes to 252Cf neutron irradiation at dose rates of 0.05 cGy/min, with (Group 1) or without (Group 2) filtering through a 10 cm thick iron block, 0.8 cGy/min (Group 3) or 0 (Group 4 controls). Total neutron exposure was 50 cGy in each of groups 1-3 and total irradiation dose was 56, 75 and 75 cGy in Groups 1-3, respectively. Total tumor incidences or multiplicity were significantly higher in Group 3 than in Group 1. A similar tendency was observed as compared to Group 2, ovarian and Harderian gland tumors being mainly affected and adrenal tumors were significantly higher in Group 2 than in Group 1. The results indicated a clear increase in tumorigenesis with the higher dose rate and no filtering influence of iron was evident, despite the drop in neutron energy level.
authors.affiliation: Department of Cancer Research, Hiroshima University, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Watanabe
authors.forename: T
authors.initials: T
authors.lastname: Okamoto
authors.forename: K
authors.initials: K
authors.lastname: Yamada
authors.forename: Y
authors.initials: Y
authors.lastname: Ando
authors.forename: A
authors.initials: A
authors.lastname: Ito
authors.forename: M
authors.initials: M
authors.lastname: Hoshi
authors.forename: S
authors.initials: S
authors.lastname: Sawada
mesh_terms: D000818:Animals; D005260:Female; D051379:Mice; D008815:Mice, Inbred Strains; D009381:Neoplasms, Radiation-Induced / Q000209:etiology*; D009678:Nuclear Energy; D009680:Nuclear Fission; D011829:Radiation Dosage