Abstract: An apparatus for the linear acceleration of electrons, particularly for intraoperative radiation therapy, including:an articulated structure for moving a radiating head that comprises an acceleration structure constituted by a plurality of cavities;a modulator for generating, controlling, and transmitting a radio-frequency to the cavities of the acceleration structure; andprocessing and control devices adapted to control the apparatus; the modulator is separate from the radiating head and the connection occurs by virtue of waveguide means adapted to carry the radio-frequency to the acceleration structure.