R6.2: Generation Of Survival Curves

Cell survival curves are typically created using in-vitro or in-vivo assays (described in predictive assays). In vitro assays typically involve plating a number of cells following irradiation, whereas in vivo assays involve inoculating a creature (usually a cloned mouse) with a set number of irradiated cells and measuring the number of colonies that form in the spleen or lung. The use of identical growth conditions (or the cloned animal) allows comparisons to be made in cell survival following different amounts of irradiation.
The plating effectiveness is the number of cells which form colonies in whatever assay method is used. A control group is used to determine the control plating effectiveness (PEcontrol) – the number of cells that form colonies in the absence of radiation. This is then used as a correction factor when examining the other groups.
The treated plating effectiveness (PEtreated) in the irradiated groups is lower due to cell death from radiation.
The surviving fraction is equal to $\text{SF}=\frac{\text{PE}_{\text{treated}}}{\text{PE}_{\text{control}}}$ and should be equal to or less than 1.
By measuring the surviving fraction following different quantities of radiation, it is possible to generate a cell survival curve by plotting the surviving fractions against dose.