Dose-dependence of the time of appearance of lung damage in mice given thoracic irradiation.

Male CBA mice were given X-radiation to the thorax in the range 7 to 23 Gy and their response was quantified by measuring ventilation rate and carbon monoxide uptake at intervals up to 2 years thereafter; their survival was also documented. The two functional end-points were similarly sensitive indicators of lung damage. Radiation damage was not observed below 10 Gy. As radiation dose was raised above this level there was a rapid shortening of the time to the appearance of damage and subsequent death. At a dose of 15 Gy the median survival time was 14 weeks but raising the dose above this level only slightly reduced the survival time. The way in which the time of survival after lung damage depends on dose is an important characteristic of the development of radiation-induced lung damage which should be considered when examining factors that may influence the development of radiation-induced lung damage.