The application of flow cytometry for the quantification of the response of experimental tumors to irradiation.

R1H rhabdomyosarcomas of the rat were irradiated with 15 Gy of x-rays and the depopulation and repopulation of the tumor was determined by means of flow cytometry, quantitative histology and colony assays. The results show that flow cytometry yields important information about the cell population kinetics of irradiated tumors, but misleading results are obtained if flow cytometry is not combined with the determination of the numerical density of cells.