Peacock, J. H. and Eady, J. J. and Edwards, S. and McMillan, T. J. and Steel, G. G. (1992) The Intrinsic /β Ratio for Human Tumour Cells: Is It a Constant? International Journal of Radiation Biology, 61 (4). pp. 479-487. ISSN 0955-3002
Full text not available from this repository.Abstract
The radiation response of 15 mammalian cell lines comprising 11 human tumour, two human fibroblast and two murine lymphoma cell lines, has been analysed using the linear-quadratic equation. As well as using conventional analysis of acute dose-survival curves to derive values for and β (termed ac and βac), low dose-rate and split-dose experiments have been used to derive independent values of and β (ldr and βRR), respectively. ldr provides a measure of irrecoverable damage, the magnitude of which agreed well with the initial slope of the acute survival curve for most cell lines. βRR derived from split-dose experiments represents a unique measure of recovery for each cell line. Large differences were found between individual values of βac and βRR, especially in the radiosensitive cell lines. Since βRR is a functional measure of recovery we suggest that this is the more relevant parameter in studies of dose sparing. The most striking result of this analysis was found in considering the /β ratios. No relationship was observed between ac and βac resulting in values of ac/βac ranging from 1 to 175. In contrast a positive correlation was observed between ldr and βRR in the 11 tumour cell lines, giving an /β ratio of 9·4 ± 1·8 Gy. This observation of the relative constancy of the ratio for human tumour cells leads to an hypothesis about the role of initial damage as a determinant of radiosensitivity.