For other radiosensitive tissue reactions, thespectrum of their occurrence, severity and macroscopic featuresis so large that their definition of reactions is still not consensual:in practice, recognition that a patient effectively suffers from asignificant tissue reaction still relies solely on subjective clinicaljudgement. Discounting dosimetry errors, these tissue reactionsare the clinical signs of one common biological feature: individualradiosensitivity. Here, the radiosensitivity term is associatedwith the notion of radiation-induced cellular death and not withthat of cancer proneness