Proliferation of lethally damaged mammalian cells irradiated by fast electrons, fast neutrons, α particles, and pions.

Proliferation of lethally damaged tumor cells was determined after irradiation with fast electrons, fast neutrons, α particles, and pions in the peak and plateau of the depth dose curve. The method used was measurement of the proliferation of the total population, N(tot), and the subpopulation of viable cells which are able to grow to macrocolonies after irradiation, N(m). The difference between these populations (N(tot) - N(m)) then represents the lethally damaged cells. The number of cell divisions after irradiation decreases with increasing absorbed dose in the same way for all the different types of radiation if related to the survival of cells, S. Consequences for the type of lethal radiation damage in mammalian cells and for radiotherapy are discussed