Radiobiology > Biologic Interactions > Cel Survival Curve > Curve Indices -- D0 and D1

Cell Survival Curve: Indices

From the cell survival curve, various indices are calculated. 

D1 and D0 are two such entities. 

  • D1 is the initial slope of the survival curve
  • D0 is the final slope of the curve - where the curve approximates a straight line. 

D0 is also a means of representing the relative radiosensitivity of cell populations.  D0 is the dose required to reduce the surviving fraction to 37% of that associated with the previous dose. 

The D0 will vary according to cell type as well as the local environment in which the cell population is cultured (e.g. oxygen tension – recall oxygen increases likelihood of free radical production).  

For oxygenated mammalian cells, D0 is about 150 rads (1.5 Gy).

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