Intra-operative interstitial brachytherapy in a novel infra-zygomatic approach for partially resectable head and neck cancers around the base of skull: A technical note

PURPOSE: To report an intra-operative catheter insertion technique into the base of skull tumor bed following surgical resection for maxillary tumors. MATERIAL AND METHODS: A 42-year-old male patient diagnosed with carcinoma of the maxilla was treated with neoadjuvant chemotherapy followed by chemo-radiation using external beam technique combined with brachytherapy boost to post-operative bed. Brachytherapy was delivered via intra-operative catheter placement at the base of skull to residual disease, which was surgically unresectable. Initially, catheters were placed cranio-caudally. This was later changed into an infra-zygomatic approach to improve planning and dose coverage. High-risk clinical tumor volume (CTV) was generated with a 3 mm margin to residual gross tumor. Planning was done using Varian Eclipse brachytherapy planning system, and an optimal plan was generated. CONCLUSIONS: An innovative, beneficial, and safe brachytherapy approach is necessary in a difficult and critical area, such as the base of skull. Our novel method of implant insertion through infra-zygomatic approach resulted in a safe and successful procedure.