The Effect of Nasopharyngeal Carcinoma's IMRT on Salivary Gland Function

Objective To evaluate the salivary glands function after intensity modulation radiated therapy(IMRT)of nasopharyngeal carcinoma.Methods 43 patients with nasopharyngeal carcinoma(NPC)were treated by IMRT for the first time.SPECT radioactive dynamic imaging was used to investigate the possibility of quantitative evaluation of salivary gland function of NPC patients before and after radiotherapy,and 3 months after radiotherapy.Results From dose-volume histogram,the mean dose,D50 and D33 of both salivary glands were remarkably different.The intake rate of the normal salivary gland before radiotherapy,after radiotherapy and 3 months after radiotherapy was 3.82%,2.08% and 2.34%,respectively;the excretion rate was 65.27%,18.01% and 31.46%.The intake rate of the affected salivary gland before radiotherapy,after radiotherapy and 3 months after radiotherapy was 4.41%,2.59% and 3.25% respectively;the excretion rate was 66.05%,20.26% and 45.73%.Function of both sides decreased apparently after radiotherapy,but without difference.The function of salivary gland of the normal side recovered 3 months after radiotherapy better than that of the affected side(P 0.01).Conclusion IMRT decreases the dose of radiotherapy.Because of the prefect dose distribution,the dose for the normal salivary glands is lower than for the affected and the normal recovers faster than the affected.