Abstract
Cell survival study is fundamentally important in radiation biology. However, the survival rate cannot be measured by the conventional technique used for uniformly irradiated population, since irradiated and non-irradiated cells are located in the same dish in the microbeam experiments. Therefore, we have tried to establish a method to measure the survival fraction appropriate for the microbeam experiments. Clear difference was observed between the histograms of the number of cells per colony for irradiated (6 to 12 Gy) cells and for non-irradiated cells after 60 hr incubation. Therefore, the threshold to determine live or dead was set between the peaks of the histogram. Survival fractions thus determined was found to depend upon the beam size of microbeam X-rays at the same exposure time. Studies with broad-beam are now under way for comparison. It is also necessary to consider how to evaluate the absorbed dose in microbeam experiments. [J Radiat Res 44:444 (2003)]
