[Probabilities of organs at risk damage: history and mathematical models]. / Probabilités de lésion des organes à risque: historique et principaux modèles mathématiques d'estimation.

The a priori evaluation of normal tissue complication probability is an important issue for the radiation oncologist looking for the best therapeutic index. The advances in radiobiological and technological knowledge provide a better understanding of the determinants of radiation effects. The amount of information required to optimize the treatment modalities justifies the use of mathematical models linking the treatment characteristics (dose, volume, treatment time...) to the likelihood of complications. The radiation oncologist needs a minimal understanding of the mathematical models and their limits to justify his prescriptions.