CO-60-GAMMA AND NEGATIVE PI MESON IRRADIATION OF MICROVASCULATURE

Neovascularization was induced surgically in normally avascular canine corneas to study the radioresponse of slowly proliferating capillary endothelial cells. Neovascularization was stimulated for 7 days. Corneal tissue samples were evaluated quantitatively by morphometric methods. Dose-response curves were drawn by plotting per cent capillary volumes versus dose. Irradiation was given with either 60Co γ-rays or 168 MeV/c negative pi mesons. The dose rate for pi mesons was about 30 rad/min. The D0 was 265 rad for γ-rays and 155 rad for pions. The ratio of D0 values gave a relative biologic effectiveness (RBE) of 1.7. Using 60Co as a standard, an RBE of 1.6 was calculated at the 1% capillary volume level. © 1978.