广义等效均匀剂量优化方法在鼻咽癌调强放射治疗计划中的应用研究

Application of generalized equivalent uniform dose optimization in the treatment of nasopharyngeal carcinoma with intensity-modulated radiotherapy

背景与目的:在制订鼻咽癌的调强放射治疗(intensity-modulated radiotherapy,IMRT)计划时,通过比较传统的剂量-体积(dose-volume,DV)物理优化方法,与联合运用DV物理优化方法和广义等效均匀剂量(generalized equivalent uniform dose optimization,gEUD)优化方法的鼻咽癌放疗计划中的剂量学差异,探讨不同的优化方法对IMRT计划中危及器官(organ at risk,OAR)的保护作用。方法:随机选取2019—2021年复旦大学附属眼耳鼻喉科医院收治的鼻咽癌患者50例,将每例计划都同时采用两组优化方案进行优化计算:A组仅采用传统的DV物理优化方法;B组采用联合DV优化和gEUD优化方法,其中gEUD的a值分别选取1、2、5、10和20。通过分别观察采用不同的优化方案及不同的a值所获得的腮腺和口腔等OAR的剂量数据结果,从而评估两组优化方案的剂量学差异。结果:比较分析两组方案的计划数据,其中靶区的剂量学指标差异无统计学意义(P>0.05)。但在腮腺和口腔的保护方面,B组优化方案的结果明显优于A组。对腮腺和口腔而言,gEUD的a值对腮腺和口腔平均剂量的影响比较明显。结论:鼻咽癌放疗计划中,联合使用物理优化和生物优化能在满足靶区剂量要求的同时,更好地保护腮腺和口腔等较大体积的并联性OAR。

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.