Fitting techniques of cell survival curves in high-dose region for use in stereotactic body radiation therapy.

Stereotactic body radiation therapy (SBRT) uses high doses of radiation to treat tumors. The cell survival behavior at these high doses is subject to debate. We investigated this high-dose region by fitting a variety of formulas to cell survival data. Each of the formulas is motivated by a discussion of the theory of cell survival. Fourteen cell lines are examined. These are fit to a variety of equations. Among the equations include the traditional single-hit multi-target and linear quadratic as well as recent proposals such as the universal survival curve (USC). The chi(2)/df of each fit is compared to determine the best fit. While no formula is clearly superior for all cell lines, the newer formulas often provide better fits than the single-hit multi-target and linear quadratic. We recommend that the more recent formula discussed herein be used over the linear quadratic in dealing with the high-dose regions dealt with in SBRT.