An apparatus for the linear acceleration of electrons, particularly for intraoperative radiation therapy, characterized in that it consists of an articulated self-propelling structure (50) for moving irradiation means that comprises:

-- an acceleration structure constituted by a plurality of cavities (26);
-- modulation means (33) for generating, self-controlling and transmitting a radio-frequency to said cavities of said acceleration structure;
-- processing and control means (40) adapted to control said apparatus, said modulation means being separate from said irradiation means, the connection occurring by virtue of wave-guide means (38) adapted to carry the radio-frequency to said acceleration structure;
-- a forked bearing (71) supporting the radiating head (32) and connected to the frame (72) by means of a rotation fifth wheel performing the rolling motion of the forked bearing (73) and of the radiating head, within which the rotating joint and the section of the flexible wave guide are located;
-- a radiating head, connected to the forked bearing through pivots having their axis orthogonal to the rolling axis and performing the pitching motions;
-- a radiation shield (62) under the treatment couch, whose centring system depends of an ultrasound transducer system.