Studies of the dose-effect relation

Dose-effect relations and, specifically, cell survival curves are
surveyed with emphasis on the interplay of the random factors —
biological variability, stochastic reaction of the cell, and the
statistics of energy deposition —that co-determine their shape. The
global parameters mean inactivation dose, , and coefficient of
variance, V, represent this interplay better than conventional
parameters. Mechanisms such as lesion interaction, misrepair,
repair overload, or repair depletion have been invoked to explain
sigmoid dose dependencies, but these notions are partly synonymous
and are largely undistinguishable on the basis of observed dose
dependencies. All dose dependencies reflect, to varying degree, the
microdosimetric fluctuations of energy deposition, and these have
certain implications, e.g. the linearity of the dose dependence at
small doses, that apply regardless of unresolved molecular
mechanisms of cellular radiation action.