In vivo measurements with MOSFET detectors in oropharynx and nasopharynx intensity-modulated radiation therapy.

PURPOSE: To evaluate the feasibility of in vivo measurements with metal oxide semiconductor field effect transistor (MOSFET) dosimeters for oropharynx and nasopharynx intensity-modulated radiation therapy (IMRT). METHODS AND MATERIALS: During a 1-year period, in vivo measurements of the dose delivered to one or two points of the oral cavity by IMRT were obtained with MOSFET dosimeters. Measurements were obtained during each session of 48 treatment plans for 21 patients, all of whom were fitted with a custom-made mouth plate. Calculated and measured values were compared. RESULTS: A total of 344 and 452 measurements were performed for the right and left sides, respectively, of the oral cavity. Seventy percent of the discrepancies between calculated and measured values were within +/-5%. Uncertainties were due to interfraction patient positions, intrafraction patient movements, and interfraction MOSFET positions. Nevertheless, the discrepancies between the measured and calculated means were within +/-5% for 92% and 95% of the right and left sides, respectively. Comparison of these discrepancies and the discrepancies between calculated values and measurements made on a phantom revealed that all differences were within +/-5%. CONCLUSION: Our experience demonstrates the feasibility of in vivo measurements with MOSFET dosimeters for oropharynx and nasopharynx IMRT.

Role of brachytherapy in treatment of epidermoid carcinomas of the vallecula after conservative supraglottic laryngectomy followed by irradiation.

PURPOSE: To evaluate survival and functional results of the treatment of carcinomas of the vallecula using surgery, irradiation, and interstitial brachytherapy. METHODS AND MATERIALS: Between 1990 and 1998, 36 patients with squamous cell carcinoma of the vallecula were treated with horizontal supraglottic functional laryngectomy, external beam radiotherapy (median dose 54 Gy), and additional interstitial brachytherapy (median dose 16 Gy). Results were compared with a previous series of 22 patients treated without brachytherapy. RESULTS: The median follow-up was 44 months. The 5-year actuarial overall survival rate was 61.3%. The 5-year specific survival rate was 86%, with 2 local failures (local control rate 94.4%) and 4 isolated distant metastases. Ten patients developed a second primary. The overall survival was 34% for 22 patients previously treated without brachytherapy. Severe toxicities occurred in 9 patients: death (related to larynx edema or inhalation, n = 1), soft tissue necrosis (n = 1), aspiration pneumonia (n = 1), mandibular necrosis (n = 2), pharyngocutaneous fistula (n = 2), and laryngeal edema (n = 2). All the patients fed orally with no definitive gastrostomy or tracheotomy. CONCLUSION: Additional brachytherapy for vallecula carcinoma seems to improve locoregional control and overall survival dramatically. Functional results were also excellent. To our knowledge, this original therapeutic schedule has never been previously described.