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Purpose: Brachytherapy re-irradiation may offer an alternative re-treatment of recurrent head-and-neck cancer even after previous full dose radiation therapy. The purposes of this study were to determine the feasibility and accuracy of frameless image-guided interstitial needle implantation., Methods and Materials: Between January 2000 and March 2003, 14 patients with biopsy-proven locally recurrent head-and-neck-cancer were retreated after previous full dose irradiation with combined external beam-brachytherapy with concomitant chemotherapy. Brachytherapy needle implantation was virtually planned taking into account the surrounding risk structures. Needles were implanted using an adapted frameless navigation system. Chemoradiotherapy was followed by 2-4 courses of chemotherapy every fourth week starting 4 weeks after the end of brachytherapy., Results: The 1- and 2-year local control rates were 78% and 57%, respectively. Local control was obtained in 8/14 patients. The actuarial 1- and 2-year survival rates were 83% and 64%, respectively. The median survival was 28 months after a median follow-up of 21 months (range, 8-53). Six weeks after brachytherapy, 1 patient developed localized soft tissue necrosis which did not require surgical intervention. No additional grade III or IV late toxicity was seen after re-irradiation. Mean deviation of image-guided needle implantation was 3.4 mm for each needle (SD, 1.9 mm; range, 0.5-14 mm). The mean deviation of all needles of an implant was 4.3 mm (range, 2.3-8.6 mm)., Conclusions: These data demonstrate that pulsed-dose-rate brachytherapy in combination with sequential chemotherapy is effective and safe in re-irradiation of locally recurrent oropharyngeal carcinomas and can be offered to patients with curative intent. Image guidance allows virtual planning and navigated implantation of brachytherapy needles with regard to optimized needle distribution and risk structures.

Purpose: To integrate MRI into CT-based 3D-brachytherapy treatment planning using a software system for image registration and fusion., Methods and Materials: Sixteen patients with recurrent head-and-neck cancer, vulvar cancer, liposarcoma, and cervical cancer were treated with interstitial (n=12) and endocavitary (n=4) brachytherapy. CT and MRI scans were performed after implantation and prior to treatment planning. Image registration to integrate the CT and MR information into a single geometric framework was performed using a software algorithm based on mutual information. Conventional 3D-brachytherapy planning based on CT-information alone was compared to brachytherapy planning based on fused CT and MRI data. The accuracy of the image fusion was measured using predefined corresponding landmarks in the CT and MRI data., Results: The presented automated algorithm proved to be robust and reliable (mean registration error 1.8 mm, range 0.8-4.1 mm, SD 0.9 mm). Tumor visualization was difficult using CT alone in all cases. Brachytherapy treatment planning based on fused CT and MRI data enabled better definition of target volume and risk structures as compared to treatment planning based on CT alone., Conclusions: Image registration and fusion is feasible for afterloading brachytherapy treatment planning. Treatment planning based on fused CT and MRI data resulted in improved target volume and risk structure definition.