Dependence of cell survival on instantaneous dose rate of a linear accelerator

Background and purpose: With the development of flattening filter-free linear accelerators for radiotherapy, the instantaneous dose rate has increased by approximately a factor 4. This leads to the question of whether there may be a radiobiological consequence. The present study investigates the radiobiological effect of this high instantaneous dose rate on two cell lines. Materials and methods: A Varian Trilogy TX linear accelerator was used to directly compare the effect of three different dose rates (5.01, 9.99 and 29.91 Gy/min, with instantaneous dose rates in the pulse of 56.5, 112.8 and 338 Gy/s) on clonogenic survival. V79 and FaDu(DD) cells were irradiated with doses in a range from 1 to 10 Gy in order to obtain dose response curves. Results: For both cell lines, there is not observed any effect of the instantaneous dose rate on cell survival. (C) 2011 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 101 (2011) 223-225