RESUMO
Objective To investigate the effects of reducing the auditory organ dose by limitation of sub regional auditory organ in IMRT plan. Methods Total 223 cases of nasopharyngeal carcinoma patients were divided into group A and group B. In group A, the IMRT plans of 114 patients were designed by limiting overall auditory organ dose. In group B, the IMRT plans of 109 patients were designed by limiting sub regional auditory organ dose. According to the Clinical prescription, the IMRT plans were designed. Paried t?test was difference between groups. Results By comparing the two groups of auditory organ dose, in all stages, the tympanic cavity Dmean average in group B decreased by T1 vs. 17?? 7%,T2 vs. 22?? 4%,T3 vs. 15?? 7% and T4 vs. 14?? 2% ( P= 0?? 000,0?? 000,0?? 000,0?? 000);cochlea Dmean average decreased by T1 vs. 11?? 0%, T2 vs. 20?? 1%, T3 vs. 10?? 0% and T4 vs. 9?? 0%(P= 0?? 004,0?? 000,0?? 007,0?? 036);vestibule Dmean average decreased by T1 vs. 22?? 6%, T2 vs. 31?? 8%, T3 vs. 20?? 6% and T4 vs. 21?? 4%, significantly less than in group A (P= 0?? 000,0?? 000,0?? 000,0?? 000). The bony portion of eustachian tube Dmean average in group B decreased were not significantly less than in group A (decreased by 3?? 4%,6?? 8%,3?? 6%,0?? 1%;P= 0?? 291, 0?? 006,0?? 155,0?? 963). Conclusions In IMRT plan, optimization on dose limitation of sub regional auditory organs were used to reduce the auditory organ dose and decrease the radiation damage to auditory organ.