Exploring chronomodulated radiotherapy strategies in a chaotic population model

We present a simple nonlinear model describing the population dynamics of cancerous, healthy, and effector cells submitted to ionizing radiation. We examine the situations in which intermittently high doses of radiation affect the cells as it occurs in radiotherapy. We characterize the effect of various irradiation parameters, such as the total delivered dose for a given standard dose rate and the number of treatment sessions seeking situations that optimize normal cells survival. In other words, we are interested in enhancing the effectiveness of a radiotherapy treatment by adjusting the temporal pattern of the dose deliverance through an exhaustive dynamical characterization of the system. This includes the study of the parameter planes, the populations’ dynamical behavior going from fixed points to chaotic oscillations, and the basins of attraction. This work leads to counter-intuitive predictions and constitutes a step towards a model of chronomodulated radiotherapy.