The purpose of the present study was to compare the dose-response relationships for the induction of lung tumors in RFM mice after localized thoracic exposures to X rays or fission neutrons. Animals were killed 9 months after localized irradiation, their lungs were cleared, and the tumors were counted to determine both percentage incidence and tumors/mouse. From these data, the relationship between tumors/mouse and X-ray dose could be described adequately by a linear-quadratic model with a shallow initial slope, or by a threshold model with a dose-squared response above the threshold dose, and linearity could be rejected over the dose range of 0 to 900 rad. For neutrons the relationship between tumors/mouse and dose over the range of 0 to 25 rad could be described by a linear, or a threshold model with linear response above the threshold. In either case, the relative biological effectiveness increased with decreasing neutron dose from 25 at 25 rad to 40 at 10 rad.
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging