RADIONUCLIDE EVALUATION OF PULMONARY-FUNCTION FOLLOWING HEMITHORAX IRRADIATION OF NORMAL DOGS WITH CO-60 OR FAST-NEUTRONS

To assess the effects of therapeutic doses of radiation on regional pulmonary function, 28 dogs had serial chest radiographs and quantitative ventilation, perfusion and aerosol studies at three-, six-, nine- and twelve-month intervals after hemithorax irradiation with 60Co-gamma photons or 15-MeV fast neutrons. Findings showed marked reductions in perfusion and aerosol deposition in the irradiated lungs of dogs in the high-dose photon and neutron groups and in the medium-dose neutron group. The effects of large photon and small neutron doses were similar (neutron RBE = 4.5). Radionuclide studies were found to be useful for detecting these alterations.