Use of customized-mold brachytherapy in the management of malignancies arising in the maxillary antrum after maxillectomy: A dosimetric analysis

摘要

Purpose: To explore the feasibility of a intraoral mold high-dose rate (HDR) brachytherapy in the treatment of tumors arising in the maxillary antrum after maxillectomy and to describe the dosimetric profile of HDR brachytherapy in such an unusual location. Methods and Materials: A customized mold with four 6-French catheters was designed and produced in transparent acrylic resin. The catheters formed a soft loop that allowed the passage of the HDR source. CT-based dose evaluation in several volumes of interest, including the gross tumor volume (GTV) and several organs at risk (OARs), such as the skin of the cheek, eyeball, lens, optic nerve, optic chiasm, and spinal cord was performed. Results: Treatments were delivered uneventfully. A favorable OAR/GTV ratio was observed. The GTV D90 was covered by the 3.8Gy isodose (95% of the prescription isodose of 4Gy) and the doses received by the OARs varied between 4% and 43% of the prescription isodose for the V1cc of spinal cord and eyeball, respectively. The only structure that could not be adequately spared was the skin overlying the tumoral lesion that received between 94% and 107% of the prescription isodose (1.0 and 0.5cm2 of skin, respectively). Conclusions: Intraoral mold-based HDR brachytherapy can be used to treat tumors involving the maxillary antrum provided that access is possible through a previous maxillectomy. A dose reduction of 4-43% in several OARs, such as the spinal cord, pituitary gland, optic chiasm, optic nerve, eyeball, and lens, is obtained.