Figure 5: Typical assembly of a modern linear accelerator with cone beam CT. a-b – unit, which works with MV-irradiation (treatment unit). C-D – unit, which works with kV-irradiation (to get a CT image). P – movable couch for patient positioning with tool for head fixation. a – MV-irradiation source, b – digital MV-image converter to check patient position with the treatment beam, C – kV-x-ray generator, D – kV-image converter to acquire CT-data.