Influence Of Dose Limitation With Inner Ear To Sensorineural Hearing Loss In The Treatment Of Nasopharyngeal Carcinoma With Volumetric Modulated Arc Therapy

Objective: A retrospective study was peformed to investigate the influence of dose limitation with inner ear to sensorineural hearing Loss in the treatment of nasopharyngeal carcinoma with Intensity-modulated radiotherapy.Patients and methods: Totally 86 eligible patients with nasopharyngeal carcinoma were treated with Intensity-modulated radiotherapy(Rapid Arc). We defined the inner ear as Organ At Risk(OAR) and limited the radiation dose as 45 Gy in treatment plan since January 1st, 2013. Audiometry measuring frequency-specific thresholds was performed in four time points: the day before radiotherapy, six, twelve and eighteen months after radiotherapy. According to the dose limitation in the inner ear, divided into experimental group and control group.Results: 14 patients were involved in experimental group and 13 patient were involved in control group. There is no difference between the two groups in short-term curative effect. Inner ear radiation dose was significantly decreased(P < 0.05) in experimental group. A significant statistical difference in hearing thresholds after radiotherapy was found in all patients. An obvious tendency towards reducing hearing loss with statistical significance was found in the experimental group compared to control group. There is a significant difference in the passing rate of Distortion Product evoked Oto Acoustic Emissions(DPOAE) between the two groups.Conclusion: The radiation dose of inner ear can be reduced by prescribe a limit of 45 Gy in the treatment plan of Rapid Arc, thus reduce the sensorineural hearing loss caused by radiotherapy in the treatment of nasopharyngeal carcinoma.