title: The radiation response of asynchronous cells at low dose: evidence of substructure.
abstract: Flow cytometry and cell sorting techniques have been used together with repeated measurement in an attempt to define better the radiation survival response of asynchronously dividing Chinese hamster V79-171 cells under aerobic and hypoxic conditions. Although the first two decades of cell inactivation have been examined, particular attention has been given to the low-dose range of a few grays, as used in individual radiation therapy treatments. A single linear-quadratic dose-response function was consistently unable to fit both the low-dose and high-dose data satisfactorily, suggesting a two-component response. Separate fitting of the low-dose and high-dose portions of the response yielded alpha and beta values which differed significantly (P = 0.001 to 0.002). The data are consistent with the hypothesis that the observed substructure simply reflects the presence of subpopulations of sensitive (G1-, G2-phase) and resistant (late S-phase) cells, which are resolved in these measurements. These results may have significance for certain situations in radiation therapy and in biophysical modeling of the radiation response.
authors.affiliation: Medical Biophysics Unit, B.C. Cancer Research Centre, Vancouver, Canada.
authors.forename: L D
authors.initials: LD
authors.lastname: Skarsgard
authors.forename: I
authors.initials: I
authors.lastname: Harrison
authors.forename: R E
authors.initials: RE
authors.lastname: Durand
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D000818:Animals; D002455:Cell Division / Q000502:physiology*; D002470:Cell Survival / Q000528:radiation effects*; D002478:Cells, Cultured; D004307:Dose-Response Relationship, Radiation; D013997:Time Factors