[Effectiveness of the biological action of protons and gamma-radiation on cells C3H10T1/2].

Relative biological effectiveness (RBE) of the therapeutic proton beam with an energy of 150 MeV was measured during fractional irradiation of mice fibroblasts C3H101 T1/2 by 4.0 Gy per day, 5 d/w with the total dose of 40 Gy. Lethal effectiveness of the beam at different points of modified Bragg's peak (width of the flat apex = 3.7 cm) was evaluated and effects of acute single gamma-radiation (6CO) of cells were investigated. Results were compared with the data of fractional irradiation to assess reparation processes. It was shown that survivability of the cells in three points of Bragg's peak was essentially the same but a bit higher at the point of entry. Proton RBE in the experiment was equal to zero relative to gamma-radiation. Difference between fractional and acute irradiation leveled off with rising doses; however, the reparative processes still had a place even at 20 Gy.