Effects of pulses of radiation on the survival of mammalian cells

It has been reported by Town (1967) that when HeLa cells in aerobic suspension are irradiated with single 1·3 μsec pulses of fast electrons, the radiosensitivity diminishes after a dose of ∼900 rads. This was attributed to the exhaustion of the oxygen present at the radiosensitive site in the cell, although with bacteria and many chemical systems (Dewey and Boag, 1959) doses of at least tens of kilorads are needed to consume the oxygen initially present in an air-saturated system. Neither Todd, Winchell, Feola and Jones (1968) nor Berry, Hall, Forster and Goodman (1969) were able to obtain the same result as Town (1967), although Berry et al. (1969) were able to demonstrate a diminished radiosensitivity in both HeLa and Chinese hamster cells using doses of greater than 500 rads delivered in 7 nsec.