Survival of mammalian cells exposed to ultrahigh dose rates from a laser-produced plasma X-ray source

PURPOSE: To determine whether intense laser-produced x rays have an increas ed radiation hazard. MATERIALS AND METHODS: Mammalian cells were exposed to x rays from a laser- produced plasma that produced ultrahigh peak absorbed dose rates, up to a f actor of 10(10) higher than those produced by conventional x rays used in i maging. The cell survival was studied as a function of the absorbed dose. T he survival of mammalian cells exposed to high peak absorbed dose rates wit h laser-produced x rays was compared with the survival of cells exposed to standard absorbed dose rates with conventional x-ray sources. Comparative s urvival studies were performed by using a conventional x-ray tube and a cob alt 60 source. The absorbed doses in the irradiation field were measured wi th thermoluminescent dosimeters. RESULTS: Cell survival following irradiation by filtered, laser-produced x rays with a high dose rate was not markedly different from the survival fol lowing irradiation by conventional sources. There was, however, a notable d ifference between the survival after exposure to filtered, laser-produced x rays and the survival after exposure to unfiltered laser-produced x rays. CONCLUSION: Exposure to filtered, laser-produced x rays with a high dose ra te does not lead to increased harm to mammalian cells exposed in vitro comp ared with the harm from exposure to x rays from conventional sources, which indicates that the use of high-power laser facilities for medical imaging is justified.