A system comprising a mobile imaging ring system and an elevator, wherein the mobile imaging ring system comprises a gantry shaped in a closed ring form, the gantry comprising an inner ring, a central stationary ring, a source ring arranged on one side of and configured to be independently rotatable along the central stationary ring, wherein a radiation source is mounted on the source ring so that the radiation source is rotatable around the gantry by rotating the source ring, and a detector ring arranged on the other side of and configured to be independently rotatable along the central stationary ring, wherein a radiation detector is mounted on the detector ring so that the radiation detector is rotatable around the gantry by rotating the detector ring, wherein the central stationary ring, the source ring and the detector ring are provided on the outer surface of the inner ring, and a supporting structure carrying the ring shaped gantry, the gantry being mounted to the supporting structure such that a plane defined by the ring shape of the gantry is tiltable relative to the supporting structure, wherein the elevator comprises rails and a carriage on the rails, wherein the rails are oriented in a vertical direction or an oblique direction, the mobile imaging ring system is docked to the carriage and the elevator is configured to lift the mobile imaging ring system. a gantry shaped in a closed ring form, the gantry comprising an inner ring, a central stationary ring, a source ring arranged on one side of and configured to be independently rotatable along the central stationary ring, wherein a radiation source is mounted on the source ring so that the radiation source is rotatable around the gantry by rotating the source ring, and a detector ring arranged on the other side of and configured to be independently rotatable along the central stationary ring, wherein a radiation detector is mounted on the detector ring so that the radiation detector is rotatable around the gantry by rotating the detector ring, wherein the central stationary ring, the source ring and the detector ring are provided on the outer surface of the inner ring, and an inner ring, a central stationary ring, a source ring arranged on one side of and configured to be independently rotatable along the central stationary ring, wherein a radiation source is mounted on the source ring so that the radiation source is rotatable around the gantry by rotating the source ring, and a detector ring arranged on the other side of and configured to be independently rotatable along the central stationary ring, wherein a radiation detector is mounted on the detector ring so that the radiation detector is rotatable around the gantry by rotating the detector ring, wherein the central stationary ring, the source ring and the detector ring are provided on the outer surface of the inner ring, and a supporting structure carrying the ring shaped gantry, the gantry being mounted to the supporting structure such that a plane defined by the ring shape of the gantry is tiltable relative to the supporting structure, wherein the elevator comprises rails and a carriage on the rails, wherein the rails are oriented in a vertical direction or an oblique direction, the mobile imaging ring system is docked to the carriage and the elevator is configured to lift the mobile imaging ring system.