Sparing the parotid glands and surgically transferred submandibular gland with helical tomotherapy in post-operative radiation of head and neck cancer: A planning study

Abstract

Background and purpose To evaluate the feasibility of sparing the parotid glands and surgically transferred submandibular gland (SMG) by intensity modulated radiotherapy (IMRT) in post-operative cases of head and neck cancer (HNC). Materials and methods Ten patients (larynx-2, base of tongue-4, tonsil-3, and unknown primary-1; pathologic stages III–IV) who underwent SMG transfers on the side of N0 neck along with definitive surgery were selected for this study. IMRT planning was done retrospectively using helical tomotherapy approach. Planning objective was to deliver 60 Gy to PTV1 and 54 Gy to PTV2 while maintaining the mean dose to the total parotid volume (TPV) and SMG less than 26 Gy. Results The mean dose (±SD) to the TPV and SMG were 25 ± 0.6 Gy and 23 ± 1.9 Gy, respectively. The D 95 for PTV1 and PTV2 were 59.9 ± 0.1 Gy and 54.9 ± 0.3 Gy, respectively, satisfying our planning goal for PTV coverage. The D 99 for PTV1 and PTV2 were 58.2 ± 0.7 Gy and 49.5 ± 2.2 Gy, respectively, showing that sparing the salivary glands did not result in underdosing of the PTVs. Conclusions By combining the gland transfer and IMRT, the mean dose to TPV and transferred SMG could be reduced to less than 26 Gy in post-operative patients of HNC.