Linkage effects in a model for cell survival after radiation.

A thermodynamic treatment for the effects of radiation on cell survival is proposed. The treatment is an extension of the linear-quadratic model (K.H. Chadwick and H.P. Leenhouts, Phys. Med. Biol. 13 (1973) 78) following the principles of linkage thermodynamics (E. Di Cera, S.J. Gill and J. Wyman, Proc. Natl. Acad. Sci. U.S.A. 85 (1988) 5077). Linkage effects between chemical binding to DNA and radiation action are considered, along with the synergism between different types of radiations. A simple mathematical condition is found for the additivity of radiation doses that result in an isoeffect. The resolvability of the model parameter is investigated by simulations and statistical analysis of the distributions obtained.