SECTION EDITORS

I n t r a n a s a l s t e n t for s t a b i l i z a t i o n and fixation of i n t e r s t i t i a l radioactive isotopes J a c k B. M e y e r , J r . , D.M.D.,* R o d n e y C. K n u d s o n , D.M.D., M.S.,** a n d E. B. B u t l e r , M.D.***

Wilford Hall U.S. Air Force Medical Center, San Antonio, Texas This article introduces the use of an i n t r a n a s a l stent for the s t a b i l i z a t i o n and fixation of a f t e r l o a d i n g c a t h e t e r s during interstitial radiation therapy. After c a t h e t e r s h a v e b e e n positioned to d e s i r e d locations w i t h i n the stent, they are i m m o b i l i z e d w i t h light p o l y m e r i z i n g resin. The fixation of the c a t h e t e r s to the stent a l l o w s the r a d i o t h e r a p i s t to afterload p r e d e t e r m i n e d radiation sources to desired locations. This t e c h n i q u e m a x i m i z e s tumor r e s p o n s e and m i n i m i z e s u n t o w a r d effects to normal surrounding tissues. (J PROSTHET DENT 1991;65:813-5.)

I n t r a n a s a l stents and splints have been used for the support and expansion of nasal soft tissues, to prevent obstruction of the airway, and for cosmetic reasons. 1, 2 This article introduces use of the intranasal stent for the stabilization and fixation of interstitial radiation catheters. For radiotherapy to be successful, interstitial catheters must

remain in position during treatment. Movement and dislodgment of the radioactive sources result in a nonhomogeneous dose of radiation to the tumor and can cause untoward effects to the normal surrounding tissues. This article describes a technique for proximal fixation of afterloading interstitial catheters to an intranasal stent. TECHNIQUE

The views expressed herein are those of the authors and do not necessarily reflect the views of the United States Air Force, the United States Army, or the Department of Defense. *Lieutenant Colonel, U.S. Army, DC; Fellow, Maxillofacial Prosthetics. **Lieutenant Colonel, U.S. Air Force, DC; Assistant Chairman for Maxillofacial Prosthetics. ***Major, U.S. Air Force, MC; Chief, Radiation Oncology. 10/1/20015

1. Follow impression procedures and laboratory techniques described in earlier publications 1, 2 for the fabrication of a hollow intranasal acrylic resin stent. Interim internal nares stents can be constructed of either heat-cured, light-cured, or autopolymerizing acrylic resin. The stent is tried in and adjusted until a comfortable fit is obtained. Orientation marks are placed to assist the surgeon in the proper placement of the stent.

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F i g . 1. Radiograph of sphenoid sinus reveals position of unloaded catheters.

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Fig. 2. Internal nares stent is sutured to external nares to prevent dislodgment.

Fig. 3. Light-curing polymerizing resin is adapted to each of the catheters and the stent.

2. After the tumor site is exposed, unloaded catheters are placed to the desired locations by the radiotherapist and their position is confirmed by radiographic analysis (Fig. 1). Pass the stent over the proximal end of the catheters and position it in the appropriate nasal vestibule. Secure it to the nostril with sutures (Fig. 2). 3. After the bonding agent is applied, light-curing polymerizing acrylic resin (Triad, Dentsply International Inc., York, Pa.) is adapted around each of the protruding catheters and the internal surface of the stent (Fig. 3). Do not disrupt the position of the catheters when applying the resin. 4. Pass nonradioactive "dummy" sources to the distal end of the catheters and assess their location radiographically (Fig. 4). The moldability of the uncured resin allows

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positional adjustments. When the catheter orientations are complete, use a light source to complete the polymerization of the resin and bond the catheters to the stent. At the time of therapy, the radiotherapist removes the "dummy" sources from the catheters and afterloads them with a suitable radioactive isotope. The patient is treated with a predetermined dose over a duration established by the radiotherapist. At treatment completion, the catheterintranasal stent assembly can be removed. Removal does not usually require general or local anesthesia. DISCUSSION The ease of application and versatility of light-cured resin allows the radiotherapist and members of the operating team to make positional adjustments, assess orienta-

J U N E 1991

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INTRANASAL STENT IN RADIATION THERAPY

Fig. 4. Radiograph of sphenoid sinus reveals "dummy" sources placed into catheters to assess orientation.

tion, and immobilize interstitial radiation catheters in a timely, efficient manner. Because the catheters are fixed proximally, they can be removed without an additional operating room experience. Most importantly, the stabilization of the catheters assures a fixed, predetermined homogeneous dose of radiation to the tumor.

SUMMARY The fixation of interstitial radiation catheters to an intranasal stent is described. This technique could be used to stabilize interstitial radiation catheters for the treatment

THE JOURNAL OF PROSTHETIC DENTISTRY

of sphenoid, ethmoid, internal nasal, and nasopharyngeal carcinomas. REFERENCES 1. Seals RR, Bohnenkamp LG, Paret SM. Intranasal prosthesis, splints, and stents. J PROSTHET DENT 1988;60:595-601. 2. Young JM. Internal nares prosthesis. J PROSTHET DENT 1970;24:320-3.

Reprint requests to: DR. JACK B. MEYER, JR. 487 WHEATON FORT SAM HOUSTON, TX 78234

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