Mammalian Cell Survival Response following Irradiation with 4 MeV X Rays or Accelerated Helium Ions Combined with Hyperthermia

Abstract

The effects of hyperthemia on Chinese hamster ovary [CHO] cell radioresponse were studied using either 4 MeV x rays or accelerated helium ions. Both pre- and postirradiation hyperthermic doses act to decrease the slope of the x-irradiation survival curve in a temperature-dependent manner, while the extrapolation number does not change appreciably. Pre-irradiation hyperthermic treatment has only a slightly greater dose-modifying effect than similar post-irradiation hyperthermia. For cells irradiated with He, pre-irradiation at 43.degree. C (1 h) changes the radiation survival curve slope and also the extrapolation number, implying that hyperthermia may act more readily to enhance lethal x-ray damage than lethal helium damage, while having a similar effect on the accumulation of sublethal damage for both of these radiations.