Reportage in a radiation oncology service in Switzerland. The service is equipped with the latest linear accelerator, the Truebeam. This machine carries out intensity modulation radiation therapy with one or mutiple arcs (RapidArc), adapted to all areas and types of cancer. It also allows stereotactic radiation therapy. A scanner known as the Cone Beam CT has been integrated into the TrueBeam in order to optimise treatment. It allows images to be captured during treatment in order to follow the movement of the tumor during irradiation, and to adapt the treatment in real time. Thanks to the recordings of breathing movement, the TrueBeam allows the most mobile organs and tumors to be treated while limiting uncertainties on the volume to be covered during treatment.