A medical robot for use inside an MRI includes a horizontal motion assembly, a vertical motion assembly and a controller. The horizontal motion assembly and the vertical assembly each includes a motion joint, an ultrasonic motor operably connected to the motion joint and an encoder operably connected to the ultrasonic motor. The motor and encoder are positioned proximate to the joint of the respective horizontal motion assembly and vertical motion assembly. Each motor has a cross section positioned in one of the axial and sagittal plane of the MRI. A medical instrument assembly is operably connectable to one of the moving joint of the vertical motion assembly. The controller is operably connected to the horizontal motion joint and the vertical motion joint and it is adapted to be powered off when the magnetic resonance imager is being used to collect images.
