A treatment device comprises a housing (450A) defining an aperture on a proximal end thereof, an inlet chamber (462), and an outlet chamber (463). A tubular sleeve member (489) extends from a distal portion of the housing. A cable assembly (15) is disposed within the housing via the aperture. The cable assembly includes an inner conductor (220), an outer conductor (224), and a dielectric material (222) disposed between the inner conductor and the outer conductor. A fluid-cooled shaft (410) is slidingly coupled to the tubular sleeve member (489) of the housing and in fluid communication with the inlet chamber (462) and the outlet chamber (463) of the housing.
