RADIOTHERAPY APPARATUS COMPRISING AN IMAGING RING

Radiotherapy apparatus for the delivery of an energetic beam to a target tissue in a treatment zone of said radiotherapy system, whereina) the radiotherapy apparatus comprises a rotatable gantry (1) for rotating the end (2) of a beam delivery system about a circle centered on an isocentre I and normal to an axis of rotation Z1 of the gantry (1), the path between the end (2) of the beam delivery system and the isocentre I defining a central beam axis Z2 at every rotation angle of the gantry (1) about the axis of rotation Z1 ;b) the radiotherapy apparatus comprises an imaging ring (3), said imaging ring (3) comprising a central bore (4), said imaging ring (3) comprising an imaging system for acquiring images of a patient in an imaging zone of said imaging system,c) the imaging ring (3) is located in the radiotherapy apparatus such that its imaging zone intersects the axis of rotation Z1 of the gantry, and the imaging ring (3) is mechanically coupled to the rotatable gantry (1) through a mechanical structure (6).