Dose-fractionation sensitivity of mouse kidney clonogens measured using different interfraction intervals and postirradiation assay times.
AffiliationCancer Research Campaign Department of Experimental Radiation Oncology, Paterson Institute for Cancer Research, Christie Hospital (NHS), Trust, Manchester, UK.
MetadataShow full item record
AbstractThe fractionation sensitivity of kidney clonogenic epithelial cells (X-irradiation in vivo, assay in vitro) was quantified using the linear-quadratic model. The cells were assayed either immediately after the fractionation schedule or after a time delay in order to compare the relative amounts of dose sparing due to fractionation (conventionally sublethal damage repair) and to post-irradiation delay intervals before assay (conventionally potentially-lethal damage repair). As the delay before assay was increased, there was a tendency for both alpha and beta to decrease, and as a consequence the alpha/beta ratio stayed virtually unchanged (3.3-4.4 Gy) regardless of delay time before assay. No change in survival was observed from 12 h to 6 weeks after neutron irradiation (62 MeVp-->Be), suggesting that the change observed after X-rays was due to repair rather than repopulation. As the interfraction intervals in an 8-fraction X-irradiation schedule were increased in steps from 6 h to 5 days, there was improved survival, consistent with the presence of long-term repair. These studies provide further evidence for the potential importance of long-term repair in late reacting tissues not only during but also after multifraction irradiation schedules.
CitationDose-fractionation sensitivity of mouse kidney clonogens measured using different interfraction intervals and postirradiation assay times. 1993, 26 (2):117-24 Radiother Oncol
JournalRadiotherapy and Oncology