Abstract:
Objective:To report the preliminary results of intensity modulated radiation therapy (IMRT) for 20 nasopharyngeal carcinoma patients. Methods:A total of 20 patients with nasopharyngeal carcinoma re -ceived IMRT in our hospital between January 2007and April 2008. Five patients were of stage Ⅱ, 13 patients were of stageⅢ, and 2 patients were of stage Ⅳ. The prescribed dose 69.96Gy was delivered to the gross tumor volume (PTV) and positive neck nodes (PTVnd); 59.36Gy to the clinical target volume (PTV1), cover -ing the upper neck and area around the nasopharynx; and 50.96Gy to the low neck and supraclavicular area (PTV2). The dose to 50% of the parotid was≤35Gy. The maximum dose to the lens, pituitary gland, tempo -ro-mandibular joint, mandible, and temporal lobe was 9, 54, 60, 70, and 60Gy. The maximum dose to the brainstem, spinal cord, optic nerve and optic chiasma (PRV) was 54, 40, 54, and 54Gy, respectively. All of the patients received 1 or 2 circles of chemothrapy before IMRT. Results: The median follow-up time was 14 months. The one-year overall survival was 94.1%. One patient died of osseous metastasis and respiratory fail-ure and 3 patients developed distant metastasis. Acute toxicity was mostly Grade Ⅰto Grade Ⅱ. Seventeen patients had grade Ⅰxerostomia. Three patients suffered from grade Ⅰacute oral mucosa reaction and 12 patients had grade Ⅱacute oral mucosa reaction. Analysis of the dose-volume histograms (DVHs) showed that the mean dose delivered to the PTV, PTVnd, PTV1 and PTV 2 was 73.4, 74.1, 67.8, and 54.1 Gy, respec -tively. The median dose to 50% of the right and left parotid glands was43.9 Gy and41.9 Gy, respcetively. The average value of maximum dose to the left and right lens was8.06and 8.12Gy, respectively. The average val-ue of maximum dose to the brainstem, spinal cord, left and right optic nerve and optic chiasma PRV was 60.6, 46.6, 50.0, 55.0, and 56.0 Gy, respectively.Conclusion:IMRT can achieve satisfactory dose distribution to na -sopharyngeal carcinoma and surrounding tissues in NPC patients, protect normal tissues during the treatment and improve local control rate.