The Research Of IMRT Plan Optimization On Dose Limitation Of Sub Regional Auditory Organ

With intensity-modulated radiotherapy for nasopharyngeal carcinoma application,patients’ parotid gland effectively get protected, the radiation damage of auditory organhas been paid more and more attention.In this study,223cases of nasopharyngeal carcinoma patients were randomly dividedinto group A and group B. In group A, the IMRT plans of114patients(stage Ⅰ:27patients; stageⅡ:25patients; stage Ⅲ:38patients; stage Ⅳ:24patients) were designedby limiting overall auditory organ dose. In group B, the IMRT plans of109patients(stage Ⅰ:17patients; stageⅡ:22patients; stage Ⅲ:42patients; stage Ⅳ:28patients) were designed by limiting sub regional auditory organ dose. According to theClinical prescription, the IMRT plans were designed.By comparing the two groups of auditory organ dose, in all stages, the tympaniccavity Dmean average, cochlea Dmean average and vestibule Dmean average ingroup B were significantly less than in group A(P<0.01). In stage Ⅱ, the bony portionof eustachian tube Dmean average in group B was significantly less than in groupA(P<0.01). In all stages, brain stem Dmean average in group A was significantly higherthan in group B(P<0.01) In stage Ⅱand Ⅲ, brain stem Dmax average in group A washigher than in group B(P<0.05). In all stages, spinal cord Dmax average, spinal cordDmea average, temporomandibular joint Dmea average in group B were significantlyless than in group A(P<0.01).This study shows that, In IMRT plan, optimization on dose limitation of sub regionalauditory organ was used to reduce the auditory organ dose, protect the auditory organ,and reduce the radiation damage of auditory organ.