Effect of 50 KV Roentgen Rays and Cobalt-60 Gamma Rays on the Activity of Ciliated Cells

: A method capable of continuously recording the changes in the physiologic activity of ciliated cells during irradiation has been used to analyse the importance of photon energy for the early biologic effects of ionizing radiation. Gamma rays from 60Co and 50 kV roentgen rays were used. Important differences were demonstrated and conventional RBE values are not valid for early effects. The results are discussed and RBE for 50 kV roentgen rays has been calculated in respect to early effects of irradiation.