Photo de stock - PROTONTHERAPY MASK<BR>Protontherapy Center of Orsay, in the French region of Ile-de-France. Protontherapy is used to treat certain types of tumors. A recently developed technique, it uses a beam of protons generated by a cyclotron. With a precision of about a hundred micrometers, protontherapy leaves neighboring, healthy cells untouched and, for this reason, is an alternative to surgery in certain cases. The treatment procedure has several stages. First, the lesion to be treated is located with a scanner-dosimeter to determine the beam angle that will best treat the lesion. A treatment plan can thus be developed. The patient then lies in a custom-fitted full-body mould or sits alone in a treatment chair and wears a custom-manufactured mask to ensure the same position the during the entire treatment. With the treatment plan finished and the immobilization device in place, treatment can begin. Generally about ten sessions are necessary. Each radiation session is brief but the preparation to find the patient´s precise treatment position is time-demanding. Here, measuring for the custom-fitted mask.