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The influence of "natural" incidence on the susceptibility to tumour induction by radiation was investigated using data obtained from several experiments carried out on BC3F(1) mice exposed to single acute doses of X-rays and fission neutrons. Based on the examination of over 500 unirradiated mice, the natural incidence of malignant lymphoma was found to be 57%. Myeloid leukemia was absent in the control animals, but was observed in the irradiated mice, although with low frequency. The incidence data as a function of dose were interpreted by radiobiological models of the induction process coupled with cell inactivation. For both malignant lymphoma and myeloid leukemia the dose-response curves after X-rays were well described, assuming a quadratic model corrected for exponential cell inactivation, and those after fission neutrons by a linear model which also allowed for cell inactivation. The differences observed for each radiation quality in the shapes of the dose-response curves between the two tumour types were ascribed to the contribution of the high natural incidence in the case of malignant lymphoma. The values of the inactivation parameter are comparable to the cell inactivation probability per unit dose for the bone marrow haematopoietic stem cells.

Additional information

Authors: COPPOLA M, ENEA, CRE Casaccia, Roma (IT);COVELLI V, ENEA, CRE Casaccia, Roma (IT);DI MAJO V, ENEA, CRE Casaccia, Roma (IT);REBESSI S, ENEA, CRE Casaccia, Roma (IT)
Bibliographic Reference: Paper presented: E.S.R.B. 22nd Annual Meeting, Bruxelles (BE), Sept 11-16, 1989
Availability: Text not available
Record Number: 198911221 / Last updated on: 1994-12-01
Original language: en
Available languages: en