title: RBE of quasi-monoenergetic 60 MeV neutron radiation for induction of dicentric chromosomes in human lymphocytes.
abstract: The production of dicentric chromosomes in human lymphocytes by high-energy neutron radiation was studied using a quasi-monoenergetic 60 MeV neutron beam. The average yield coefficient [see text] of the linear dose-response relationship for dicentric chromosomes was measured to be (0.146+/-0.016) Gy-1. This confirms our earlier observations that above 400 keV, the yield of dicentric chromosomes decreases with increasing neutron energy. Using the linear-quadratic dose-response relationship for dicentric chromosomes established in blood of the same donor for 60Co gamma-rays as a reference radiation, an average maximum low-dose RBE (RBEM) of 14+/-4 for 60 MeV quasi-monoenergetic neutrons with a dose-weighted average energy [see text] of 41.0 MeV is obtained. A correction procedure was applied, to account for the low-energy continuum of the quasi-monoenergetic spectral neutron distribution, and the yield coefficient alpha for 60 MeV neutrons was determined from the measured average yield coefficient [see text]. For alpha, a value of (0.115+/-0.026) Gy-1 was obtained corresponding to an RBEM of 11+/-4. The present experiments extend earlier investigations with monoenergetic neutrons to higher energies.
authors.affiliation: Department 6.4 Ion Accelerator and Reference Radiation Fields, Physikalisch-Technische Bundesanstalt, PO Box 3345, 38023, Braunschweig, Germany. ralf.nolte@ptb.de
authors.forename: R
authors.initials: R
authors.lastname: Nolte
authors.forename: K-H
authors.initials: KH
authors.lastname: Mühlbradt
authors.forename: J P
authors.initials: JP
authors.lastname: Meulders
authors.forename: G
authors.initials: G
authors.lastname: Stephan
authors.forename: M
authors.initials: M
authors.lastname: Haney
authors.forename: E
authors.initials: E
authors.lastname: Schmid
mesh_terms: D002478:Cells, Cultured; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000235:genetics* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D005214:Fast Neutrons / Q000009:adverse effects*; D005720:Gamma Rays / Q000009:adverse effects*; D006801:Humans; D008214:Lymphocytes / Q000528:radiation effects*; D008297:Male; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D012062:Relative Biological Effectiveness