ABSTRACT
This chapter will introduce the basic linear-quadratic (LQ) equation as the most appropriate and least complicated model for describing cell inactivation by ionizing radiation. The physical conditions required during radiation exposures for cell killing to conform to the LQ model are identified. That these conditions are poorly understood and rarely met in many published studies suggests that arguments about LQ appropriateness will arise. The basic LQ model obtains for cell populations of homogenous radiosensitivity when irradiated under experimental conditions that eliminate or minimize the repair of sublesions during the radiation exposures. Consequently, survival curves produced with asynchronous populations of cells irradiated at dose-rates of about 1 Gy/min at room temperature or at 37°C will yield α-and β-values from which information about fundamental biophysical mechanism(s) will be difficult to interpret.
