A magnetic resonance guided radiotherapy device, comprising: a bore-type magnet configured to generate a static magnetic field in an examination region, the magnet being configured with a magnet radiation translucent region which allows gamma rays or x-rays radiation beams to travel radially through the bore-type magnet into a subject disposed therein; a split-type gradient coil which defines a gap including a gradient coil radiation translucent region aligned to the magnet radiation translucent region, the split-type coil being configured to apply selected magnetic field gradient pulses across the imaging region; a radiofrequency coil configured to induce and manipulate magnetic resonance in a subject in the examination region and acquire magnetic resonance data from the examination region; a radiation source disposed laterally to the bore-type magnet, the radiation source being positioned to transmit the gamma rays or x-rays radiation beams through the magnet and gradient coil radiation translucent regions (16, 20) to an isocenter of the bore-type magnet; a scanner controller which is configured to control the gradient coil and radio-frequency coil to generate an image representation; and a processor based controller programmed to perform the steps of: - acquiring a pre-treatment image representation of a target volume and non-target volumes; - determining a contour and position of the target volume and at least one non-target volume based on the pre-treatment image representation; - administering, by means of the radiation source, a radiation dose, the radiation dose including a plurality of radiation beam trajectories and a radiation beam geometry; - controlling an acquisition of a plurality of intra-treatment image representations of a target volume and non-target volumes during the administration of the radiation dose; - determining contours and positions of the target volume and at least one non-target volume based on the intra-treatment image representations; and - determining the actual radiation dose delivered to each region of the target volume and the at least one non-target volume based on their determined contours and positions from the pre-treatment image representation and the intra-treatment representations, the radiation beam trajectories, and the at least one radiation beam geometry. a bore-type magnet configured to generate a static magnetic field in an examination region, the magnet being configured with a magnet radiation translucent region which allows gamma rays or x-rays radiation beams to travel radially through the bore-type magnet into a subject disposed therein; a split-type gradient coil which defines a gap including a gradient coil radiation translucent region aligned to the magnet radiation translucent region, the split-type coil being configured to apply selected magnetic field gradient pulses across the imaging region; a radiofrequency coil configured to induce and manipulate magnetic resonance in a subject in the examination region and acquire magnetic resonance data from the examination region; a radiation source disposed laterally to the bore-type magnet, the radiation source being positioned to transmit the gamma rays or x-rays radiation beams through the magnet and gradient coil radiation translucent regions (16, 20) to an isocenter of the bore-type magnet; a scanner controller which is configured to control the gradient coil and radio-frequency coil to generate an image representation; and a processor based controller programmed to perform the steps of: - acquiring a pre-treatment image representation of a target volume and non-target volumes; - determining a contour and position of the target volume and at least one non-target volume based on the pre-treatment image representation; - administering, by means of the radiation source, a radiation dose, the radiation dose including a plurality of radiation beam trajectories and a radiation beam geometry; - controlling an acquisition of a plurality of intra-treatment image representations of a target volume and non-target volumes during the administration of the radiation dose; - determining contours and positions of the target volume and at least one non-target volume based on the intra-treatment image representations; and - determining the actual radiation dose delivered to each region of the target volume and the at least one non-target volume based on their determined contours and positions from the pre-treatment image representation and the intra-treatment representations, the radiation beam trajectories, and the at least one radiation beam geometry. - acquiring a pre-treatment image representation of a target volume and non-target volumes; - determining a contour and position of the target volume and at least one non-target volume based on the pre-treatment image representation; - administering, by means of the radiation source, a radiation dose, the radiation dose including a plurality of radiation beam trajectories and a radiation beam geometry; - controlling an acquisition of a plurality of intra-treatment image representations of a target volume and non-target volumes during the administration of the radiation dose; - determining contours and positions of the target volume and at least one non-target volume based on the intra-treatment image representations; and - determining the actual radiation dose delivered to each region of the target volume and the at least one non-target volume based on their determined contours and positions from the pre-treatment image representation and the intra-treatment representations, the radiation beam trajectories, and the at least one radiation beam geometry.