Multivariate Analysis of the Influence Factors on the Short-term Parotid Gland Function of Nasopharyngeal Cancer Undergoing Intensity-modulated Radiotherapy

[Purpose] To summarize the influence factors on post-irradiation parotid gland function of nasopharyngeal cancer(NPC)undergoing intensity-modulated radiotherapy(IMRT).[Methods] The dosimetric parameters of tumor target and the parotid from 20 cases with NPC undergoing primary IMRT between July 2008 and August 2009 were collected.Xerostomia at 3 months after radiotherapy was investigated.The relationship between xerostomia and parotid dose received was analyzed.[Results]Of the 20 NPC undergoing IMRT the mean dose of the parotid was 41.25Gy.V20,V30,V40 of the ipsilateral parotid gland were 96.77%,80.56%,52.43%,respectively,and V20,V30,V40 of the contralateral parotid gland were 91.47%,69.95%,40.85%,respectively.The mild,moderate,and severe xerostomia rate were 15%,55%,30%,respectively at 3 months after radiotherapy.Xerostomia positively correlated to the mean dose of the parotid glands,V20,V30,V40 of the ipsilateral parotid gland and contralateral parotid gland.[Conclusion]The parotid gland function after IMRT in NPC patients only significantly correlates to the irradiated volume and dose on parotid gland.