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Background and purpose: In the design of intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma, the traditional dose-volume (DV) physical optimization method is compared with the combined use of the DV physical optimization method and the generalized equivalent uniform dose (gEUD) optimization. This study aimed to investigate dosimetry differences in radiotherapy planning for nasopharyngeal carcinoma using gEUD method, to explore the effect of different optimization methods on the protection of organ at risk (OAR) in IMRT planning. Methods: Fifty patients with nasopharyngeal carcinoma in Eye & ENT Hospital of Fudan University from 2019 to 2021 were randomly selected, and two optimization plans were used for each case at the same time for optimization calculation. Group A used the traditional DV physical optimization method, while group B combined DV optimization and gEUD optimization methods adopted, in which gEUD was selected as a=1, 2, 5, 10 and 20. We evaluated the results of OAR dose data obtained by using different optimization schemes and different a values. Results: The planned data of the two plans were compared and analyzed, and there was no statistically significant difference in the dosimetry index of the target area between groups (P>0.05). However, in terms of the protection of the parotid gland and oral cavity, the results of the optimization plan of group B were significantly better compared with group A. The a value of gEUD had more obvious influence on the average dose of the parotid gland and the oral cavity. Conclusion: In the radiotherapy plan for nasopharyngeal carcinoma, the combined use of physical optimization and biological optimization can not only meet the target dose requirements but also better protect the parotid gland, oral cavity and other endangered OAR. |
