Direct correlation between cell loss and depression of labeled thymidine incorporation after irradiation. I. Spleen.

The object of this investigation was to determine the relationship between depression of DNA synthesis and cell loss in the spleen after single small radiation doses and to determine whether DNA synthesis after exposure to different radiation modalities can be used as a measure of radiation sensitivity and relative biological effectiveness (RBE). The results presented illustrate, for the first time, that depression of DNA synthesis and cell loss in the spleen after small single doses of irradiation are directly correlated. This correlation indicates that depression of labeled thymidine incorporation and cell loss can be used to determine tissue sensitivity to irradiation. Advance determination of depression of labeled thymidine incorporation or cell loss, using small radiation doses from different radiation modalities, can establish cell killing efficiency and RBE values for each proliferating tissue.