Lack of dose rate modification (0.0049 vs. 0.12 Gy/min) of fission-neutron-induced neoplastic transformation in C3H/10T1/2 cells.
Clonogenic survival and neoplastic transformation of asynchronous cultures of C3H/10T1/2 cells were used to assay the effect of dose protraction of reactor-produced fission neutrons. Cells were exposed to eight neutron doses ranging from 0.05 to 0.9 Gy delivered at 11.7 or at 0.49 cGy/min. For each dose level, high and low dose rate irradiations were performed on the same day. At each dose a similar effectiveness of fission neutron irradiation at high or low dose rates was measured for both cell survival and transformation. The combined high and low dose-rate data were analysed by two- or three-parameter models. Depending on the model used, values of the effectiveness per unit dose derived as parameters of linear terms of the respective dose-response curves were 0.9-1.2 Gy-1 for clonogenic survival and 5-8 x 10(-4) Gy-1 for neoplastic transformation. It is concluded that the modification of fission neutron dose-response curves by dose rate is negligible or absent in the range of doses and dose rates examined, in contrast to results with other sources of fission or fast neutrons.
Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore 21201.
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Balcer-Kubiczek
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Harrison
D000818:Animals; D002461:Cell Line, Transformed; D002470:Cell Survival / Q000528:radiation effects; D002471:Cell Transformation, Neoplastic / Q000528:radiation effects*; D002999:Clone Cells / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004735:Energy Transfer; D051379:Mice; D008809:Mice, Inbred C3H; D009502:Neutrons; D009680:Nuclear Fission; D012062:Relative Biological Effectiveness