Special Devices Used During Radiation Therapy

Special treatment devices, known as radiation stents, may provide significant benefit to the patient and radiotherapist by assisting in the delivery of the radiation to precise local areas and thereby limiting complications following therapy. Not all patients undergoing head and neck radiation therapy will have a stent fabricated. The need for a radiation device is determined by the treating radiotherapist. If a stent is to be made, it can be used to protect (shield) or displace vital structures outside the treatment field, place diseased tissues within a daily repeatable position during treatment, position the beam, or maintain radioactive material at the tumor site.

At the first appointment, impressions are usually made of the upper and lower jaws and stone models are subsequently made from those impressions. A jaw registration composed of wax is made to approximate the upper and lower jaws in the treatment position. The stone models are placed into the wax registration and mounted onto an instrument so that the jaw relationship is reproduced. The radiation device is initially prepared in wax and verified in the patient's mouth prior to it being finalized. The completed radiation stent is usually made of an acrylic resin and may or may not contain a shielding lead alloy, depending upon several conditions: type of radiation given, condition of the diseased hard and soft tissues, oral opening ability, and the needs of the treating radiotherapist. Although use of these devices is usually confined to the head and neck region, they are occasionally of advantage in other accessible areas.