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[Patient positioning and its verification: justification, state of the art of the classical practices].

Patient immobilization is considered an important part of the quality control program in radiation therapy. The need for patient immobilization according to the symptoms, ensuring both reproducibility and comfort, is described in the recommendations for level 1 published by the SFPM (Société française de physique médicale) and the SFRO (Société française de radiothérapie oncologique). A customized device, associated with regular controls, is required for level 2. Customized procedures are mandatory in clinical practice for head and neck and brain treatments. Internal margins and movements of patients must be analyzed and controlled as deviations of CTV placement relative to the isocenter of linacs. They could be reduced with efficient positioning devices and accurate customized immobilization systems. Different devices could be used according to tumor locations. Except for subclavicular tumors, their efficacy remains controversial.