Abstract: An apparatus is provided which includes a substantially flat base defining a pocket insert configured and dimensioned for receiving the treatment head module and a hydrogel in alignment with the treatment head module for preventing the attenuation of the ultrasonic waves propagated from the treatment head module during ultrasonic treatment. A portion of the apparatus which comes into contact with the patient is provided with an adhesive covered by a peel-off backing. During use, the peel-off backing is removed to expose the adhesive and the apparatus is affixed to the patient. The treatment head module is then inserted within the pocket insert. The pocket insert securely maintains the treatment head module in position without over compressing soft or injured tissue. In another embodiment thereof, the apparatus includes a hydrogel having an adhesive on opposing sides and peel-off backings covering each adhesive. During use, the peel-off backings are removed to expose each adhesive.