Tomotherapy is a new external beam radiation therapy technique using helicoidal intensity modulated radiation principle. It is able to avoid multiple isocenters requested to irradiate large volumes. This machine integrates image acquisition, treatment planning, positioning of the patient and irradiation into a sole engine. Six degrees of freedom robot coupled with a 6 MV linear accelerator, InCA has installed the Cyberknife in France in 3 sites chosen. The last generation of linac is a multifunction machine able to deliver conformal irradiations with or without intensity modulated radiation therapy, cranial or extracranial stereotactic irradiation with or without arctherapy or modulation. Performances of each machine have to be measured and compared in a medical and economical procedure.