Towards biology-oriented treatment planning in hadrontherapy.

By representing damage induction by ionising particles and its repair by the cell, the probabilistic two-stage model provides a detailed description of the main processes involved in cell killing by radiation. To link this model with issues of interest in hadron radiotherapy, a simple Bragg peak model is used. Energy-loss, its straggling and the attenuation of the primary particle fluence are represented in a simplified way, based on semi-phenomenological formulas and energy-loss tables. An effective version of the radiobiological model, considering residual (unrepaired) lesions only, is joined with the simple physical model to estimate cell survival along ions' penetration depth. The predicted survival ratios for CHO cells irradiated by carbon ions are presented, showing very good agreement with experimental data.