RÉSUMÉ
Objective To evaluate the effect of an equivalent uiform dose optimization (EUD) based optimization algorithm in sparing the organ at risk (OAR) of tumor treated with intensity-modulated radiation therapy (IMRT).Methods 10 patients of nasopharyngeal carcinoma (NPC),10 patients of esophagus cancer,6 patients of rectum cancer were randomly selected from all patients received IMRT treatment.Then physical optimization constraints (dose/dose-volume constraints) were designed as EUD optimization,while the physical objectives for targets and other OAR were unchanged.Results There was statistically significant difference in protecting OAR in 8 NPC patients of PLANED group compared with those of PLANNO_EuD group (t values were 2.590,2.352,3.656,2.148,2.283,3.683,2.192,2.353,2.146,2.276,2.126,P ＜ 0.05).There was no statistically significant difference in protecting OAR in 10 cases of esophageal cancer between PLANEUD group and PLANNO_EUD group (t value were 0.408,0.427,0.920,P ＞ 0.05).There was statistically significant difference in protecting OAR in 6 cases of rectum cancer of PLANED group compared with those of PLANNO_EUD group (t values were 2.332,2.693,2.279,2.244,P ＜ 0.05).Conclusion EUD optimization can reduce the doses to OAR which may be quite helpful to reduce the occurrence rate of OAR complications.