A Nonextensive Model for Radiobiology

A nonextensive survival fraction model is extended from single dose to fractionated radiotherapy treatments, ruled by an extensivity index and a critical annihilation dose. The expected effects of doses given simultaneously and separately in time, lead to the general expression for the survival fraction with both limits linked by a new parameter describing the evolution of tissue radioresistance. This parameter determines the critical dose per fraction needed to achieve total target annihilation. The conclusion is that as the extensivity index of the tissue characterises the primary response of the tissue to radiation, the success of fractionation depends only on this critical dose per fraction value.