The nature and relevance of late lung pathology following localised irradiation of the thorax in mice and rats

The dissociation of early and late lung damage in mice and rats irradiated to the whole thorax and the timing of pneumonitis and effusive stages for each strain is schematically summarised. An early and isolated incidence of pneumonitis was observed only in CBA mice. The absence of a prominent fibrotic pathology in the lungs of these animals is also in accordance with the clinical counterpart where the radiation doses at which widespread pneumonitis can be acceptably tolerated are at or below the lower limits of fibrosis. An independent expression of pleural effusions and the strain-related variation in response time implicates radiation damage to a separate target cell population with perhaps genetically determined variations in cell turnover. (UK)