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

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 D(90) was covered by the 3.8 Gy isodose (95% of the prescription isodose of 4 Gy) and the doses received by the OARs varied between 4% and 43% of the prescription isodose for the V1 cc 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 0.5 cm(2) 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.