Comparison between the immediate effects of photon and electron radiation on the ciliary activity of the trachea of the rabbit. An in vitro investigation.

The immediate effects of 6 MV roentgen rays and 4 MeV electron rays on the mucociliary activity of the trachea of the rabbit were studied. In spite of the same average LET for the two radiation qualities, there was a clear difference in their effects on the ciliary motility during irradiation. The increase of the mucociliary activity after an absorbed dose of 1.5 Gy roentgen rays reported earlier was confirmed by the present investigation when using 6 MV photons. Electron radiation increased the beat frequency to a corresponding degree already at an administered dose of 0.5 Gy. The differences found in the pattern of the mucociliary activity during irradiation are discussed. The results indicate that the conventional RBE values cannot be used for early physiologic effects of irradiation.