[Cartography and risk management in radiotherapy: A collaborative work of the department of radiotherapy and the department of quality and risk management at the Jean-Godinot Institute]. 
To deploy an inductive process for radiotherapy risk management in a regional cancer centre and to infer the actions required to solve the situations of criticality.  Close collaboration between the department of radiation oncology-biophysics and the department of quality and risk management in the same institution allowed to create a multiprofessional and multidisciplinary task force and to make the experience feedback easier.  A preliminary risk analysis method was used to identify the generic dangers, the mapping of risks and the specification of the scales of criticality.  This method helped to evaluate and to rate each apprehended event.  Four scales have been defined: seriousness scale in five levels, likelihood scale in five classes, endeavour scale in four levels and criticality scale in three categories: acceptable (criticality 1) tolerable under control (criticality 2) and unacceptable (criticality 3).  Fifty-seven level 1 dangerous situations linked to 78 scenarios of criticality acceptable, tolerable and unacceptable in 24, 44 and 10 cases respectively have been identified in the department of radiotherapy leading to carry out 28 risk reduction actions.  The performed risk analysis offered an original frame for a collective thinking among the care providers and contributed to modify their mode of conceiving both security and radioprotection.  The study allowed us to give a relevant answer to the High Authority of Health and the Authority of Nuclear Security demands either in terms of efficient management of the risks in radiotherapy or regarding the daily concerns of the caregivers.