Measuring Cell Survival

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    Relative Biological Effectiveness (RBE) is measured by

    RBE = Dose of 250 keV x-rays to produce effect
                Dose of test radiation to produce effect

    For a mouse it takes 450 Rads at 250 keV and 350 Rad at 662 keV (Cesium-137) to kill 50% of a mouse cell line. These number are plugged into the formula and a RBE value for that type of radiation and cell is found.

    In cell lines there is also an oxygen effect that can be measured. The oxygen reduces the probability of free radical recombination reactions in its presence.

    Page 124

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