title: Derivation and application of equations describing the effects of fractionated protracted irradiation, based on multiple and incomplete repair processes. Part 2. Analysis of mouse lung data.
abstract: General equations for fractionated protracted irradiation have been applied to the analysis of mouse lung data derived from isoeffect protocols. The data were accrued from a spectrum of different protocols including different radiation qualities, interfraction times and dose-rates. This analysis, based upon two component repair rate processes, suggests that there are possibly two repair-rate processes involved in the repair of sublethal damage in the lung. The two repair half-lives were 0.32 and 1.92 h with a low dose-rate partitioning of 1:0.38 between the amount of lethal damage resulting from rapid and slow sublethal damage repair processes at low dose-rates. The analysis also indicates that there may be a dose-rate amplification of the amount of resultant lethal damage, deriving from sublethal damage, associated with the longer repair process. It is also shown that the alpha/beta ratio is probably independent of the radiation quality and that the ratios of multiple to single event damage for 240kVp X-rays and 60Co are almost identical. However, the absolute values of alpha and beta for 240 kVp X-rays may be greater than for 60Co.
authors.affiliation: Beatson Laboratories, Department of Radiation Oncology, University of Glasgow, UK.
authors.forename: W T
authors.initials: WT
authors.lastname: Millar
authors.forename: P A
authors.initials: PA
authors.lastname: Canney
mesh_terms: D000818:Animals; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D005720:Gamma Rays; D008168:Lung / Q000528:radiation effects*; D008433:Mathematics; D051379:Mice; D008962:Models, Theoretical; D013997:Time Factors; D014965:X-Rays
chemical_list: D004247:DNA