Cell survival curve
Encyclopedia
A cell survival curve is a curve used in radiobiology
Radiobiology
Radiobiology , as a field of clinical and basic medical sciences, originated from Leopold Freund's 1896 demonstration of the therapeutic treatment of a hairy mole using a new type of electromagnetic radiation called x-rays, which was discovered 1 year previously by the German physicist, Wilhelm...
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It depicts the relationship between the fraction of cells retaining their reproductive integrity and the absorbed dose.
Conventionally, the surviving fraction is depicted on a logarithmic scale, and is plotted on the y-axis against dose on the x-axis.
Cell survival as a
function of radiation dose is graphically represented by plotting the surviving
fraction on a logarithmic scale on the ordinate against dose on a linear scale on
the abscissa.
Cell surviving fractions are determined with in vitro or in vivo techniques.
Examples of survival curves for cells irradiated by densely and sparsely ionizing
radiation beams are shown in Fig. 14.1.
The type of radiation influences the shape of the cell survival curve.
Densely ionizing radiations exhibit a cell survival curve that is almost an
exponential function of dose, shown by an almost straight line on the log–linear
plot. For sparsely ionizing radiation, however, the curves show an initial slope
followed by a shoulder region and then become nearly straight at higher doses.
Factors that make cells less radiosensitive are: removal of oxygen to create a
hypoxic state, the addition of chemical radical scavengers, the use of low dose
rates or multifractionated irradiation, and cells synchronized in the late S phase
of the cell cycle.
Several mathematical methods of varying degrees of complexity have
been developed to define the shape of cell survival curves, all based on the
concept of the random nature of energy deposition by radiation.
The linear quadratic model is now most often used to describe the cell
survival curve, assuming that there are two components to cell kill by radiation.