Patent ID: 8705696

Claim:
A radiotherapy system, comprising: a support for supporting a patient undergoing radiotherapy treatment; a gantry, rotatable about an axis; a source of radiation, mounted on the gantry, producing a beam of therapeutic radiation directed towards a target region of the patient; a collimator, coupled to said radiation source, for collimating said therapeutic radiation beam, the collimator comprising a plurality of beam-limiting elements, moveable to collectively define a shaped aperture through which the radiation beam passes; a portal imager, mounted on the gantry opposite the radiation source, for detecting the therapeutic radiation after it has passed through the patient and generating corresponding images; and associated circuitry, for controlling at least the gantry, the source, the collimator, and the portal imager, collating detected data consisting of a plurality of images acquired from the imager, the plurality including images at a plurality of angles of rotation of said gantry and images at a plurality of collimator shapes, and generating a three-dimensional image of the target region based thereon.