Methods of bolusing the tracheostomy stoma

Purpose: The tracheostomy stoma is a potential site of recurrence for patie nts who have subglottic cancer or subglottic spread of cancer. In these pat ients, it is important that the anterior supraclavicular field does not und erdose the posterior wall of the tracheostomy stoma when using a 6-MV anter ior photon field. Conventionally, this problem is surmounted with placement of a plastic tracheostomy tube, which is uncomfortable for the patient, po tentially traumatic, and can interfere with vocalization via a tracheal eso phageal puncture, Our study was designed to investigate the dosimetry of th is region and see if alternate methods would be effective. Methods and Materials: A phantom was constructed using a No. 6 tracheostomy tube as the model for the tracheostomy curvature and size. Using the water -equivalent phantom, film dosimetry, and films oriented parallel to the en face field, we investigated the dose at the depth of the surface of the pos terior wall of the phantom's tracheostomy stoma, Dose was measured both in space and at the tissue interface by scanning points of interest both horiz ontally and vertically. We measured doses with a No. 6 and No. 8 plastic tr acheostomy tube, either 0.5 cm and 1.0 cm of bolus (1-cm airhole) with no t racheostomy tube, as well as 0.3 cm and 0.6 cm tissue-equivalent Aquaplast (Med-Tec Co., Orange City, Iowa) over the tracheostomy. Dosimetry at the po sterior interface was confirmed using thermoluminescent dosimeters, Results: Three mm and 6 mm of Aquaplast produced a posterior tracheal dose of 93% and 100%, Conclusion: There is no need for these patients to wear a temporary plastic tracheostomy tube during their external radiation therapy. Aquaplast shoul d allow better position reproducibility, reduce trauma, not interfere with patient respiratory efforts, and be compatible with vocalization via a trac heal esophageal puncture. (C) 2001 Elsevier Science Inc.