A stationary assembly of computer-based devices designed to simultaneously create magnetic resonance imaging (MRI) images and deliver gamma radiation from a radionuclide source (typically cobalt) for stereotactic-radiosurgical therapy, typically to treat malignant tumours; the MRI images can be used to monitor treatment in real-time. It consists of radiation-emitting heads and collimators in a rotating gantry assembly; a magnet MRI system for soft-tissue imaging; patient couch and integrated positioning system; control consoles for image acquisition, planning and treatment administration; and integrated software.