Carotid dosimetry after re-irradiation with (131)Cs permanent implant brachytherapy in recurrent, resected head and neck cancer

PURPOSE: Permanent seed implant cesium-131 ((131)Cs) brachytherapy provides highly localized radiation for patients with recurrent head and neck cancer (HNC), who may be ineligible for external beam radiation therapy due to a high-risk of toxicity. As carotid blowout is a concern in the setting of re-irradiation, a dose to the carotid artery was examined for (131)Cs brachytherapy implants. MATERIAL AND METHODS: Eleven patients were implanted with (131)Cs adjacent to carotid at the time of resection for recurrent HNC. Vascularized tissue flaps were used in some patients. The carotid artery was contoured on the post-implant brachytherapy treatment plan, and the maximum carotid point dose and minimum carotid-seed distances are reported. The incidence of carotid blowout in the follow-up period was also measured. RESULTS: The maximum carotid dose was 77 ±52 Gy (range, 3-158 Gy). The closest seed to the carotid artery was 0.8 ±0.8 cm (range, 0.2-2.6 cm). One patient without a flap experienced carotid blowout, which was attributed to a non-healing wound rather than to high radiation doses. CONCLUSIONS: Carotid artery doses from (131)Cs are reported. Vascularized tissue flaps should be considered when planning (131)Cs brachytherapy.