[Influence of ultrafractionation on the effect of whole body uniform irradiation with protons of 1000 MeV energy].

In experiments with rats a study was made of the radiobiological influence of a pulse frequency (45.9 and 4.5 c-1) of a 1000 MeV proton beam. The estimates of metabolic parameters of the peripheral blood and spleen 24 h and the survival rate during 60 days following irradiation have demonstrated the increase in the biological effectiveness of the proton beam with decreasing pulse frequency. As to 60Co-gamma-radiation, RBE of protons was 1.10 +/- 0.04 at the pulse frequency of 9 c-1 and 0.98 +/- 0.03 at 45 c-1 as determined by the probit-logarithm dose method.