A system for providing scanning medium for scanning a volume of tissue comprising: an inner chamber that contains the scanning medium; a transducer mounted to the inner chamber and configured to move along a motion path, with the inner chamber, in scanning the volume of tissue; an outer chamber concentrically aligned about the inner chamber to guide the inner chamber along the motion path; a piston module defining a base surface within the inner chamber, the piston module comprising a medium inlet and a medium outlet for adjusting an amount of the scanning medium within the inner chamber; a detection subsystem coupled to the base surface of the piston module; and an actuator comprising a stationary portion mounted to the piston module and a moving portion coupled to the inner chamber and configured to produce motion of the inner chamber along the motion path.