Impact of Adaptive Image Guided Radiotherapy on Parotid Sparing in Head and Neck Cancer

Objectives: The aim of this study was to assess volume change in parotid glands and its clinical implication in form of late xerostomia in patients receiving adaptive radiotherapy for treatment of primary squamous cell carcinoma of head and neck region. Materials & Methods: Clinical data of 50 patients who received adaptive radiotherapy was compiled for analysis. Dosimetric assessment was done using Dose Volume Histograms (DVH). Radiation induced xerostomia was documented at week 1, 3, 5 and 7 during the treatment and at 3 and 6 months on follow up. Results: Volume reduction of right parotid was 12.98 %, 23.3 % and 33.15 % whereas percentage volume change in left parotid was 6.25 %, 16.37 % and 28.39 % at these time intervals. Thirty percent patients had grade 2 or higher salivary gland toxicity at 3 months. Fifty two percent patients were free of any xerostomia reactions at 6 months follow up and only 9 % had grade 2 or higher salivary gland toxicity. Conclusion: Volume change in bilateral parotid glands occurs continuously throughout the course of radiation treatment. Parotid gland sparing and reduction in grade 2 or higher xerostomia can be achieved with excellent precision in adaptive radiotherapy.