等效均匀剂量在宫颈癌腔内联合插植近距离治疗中的应用

目的探索等效均匀剂量(EUD)在宫颈癌腔内联合插植近距离治疗(BT)计划中的应用。方法随机选取在天津医科大学肿瘤医院接受腔内联合插植BT的宫颈癌患者20例,分别进行基于EUD和混合EUD(h-EUD)计划的优化设计,分析比较计划结果与预先的混合逆计划优化(HIPO)计划间剂量学差异。为进一步评估EUD目标在优化设计中的作用,对所有病例增加了虚拟的均匀组织间插植实验。结果3种优化计划具有相似的适形指数,与HIPO计划相比,EUD计划的膀胱、直肠、小肠平均D2cm3分别减少了0.22、0.23、0.28 Gy,平均EUD分别减少了0.14、0.20、0.15 Gy;h-EUD计划的膀胱、直肠、小肠平均D2cm3分别减少了0.16、0.22、0.24 Gy,平均EUD分别减少了0.20、0.13、0.16 Gy(P均<0.05)。在虚拟插植实验中,EUD目标能对危及器官提供更加显著的剂量改善。结论宫颈癌腔内联合插植BT采用EUD优化方法能在保证靶区剂量基本一致,并有效降低正常组织受量、改善治疗计划。

Application of equivalent uniform dose optimization in intracavitary/interstitial brachytherapy for cervical cancer

Objective To investigate the application of equivalent uniform dose (EUD) in the combination of intracavitary and interstitial brachytherapy (combined-BT) for cervical cancer. Methods Twenty cervical cancer patients treated with combined-BT in Tianjin Medical University Cancer Institute and Hospital were recruited in this study. For each patient, treatment plans were optimized based on EUD and hybrid EUD (h-EUD). The results were statistically compared with predefined plans generated by Oncentra Brachy v4.3 using hybrid inverse planning optimization (HIPO). Furthermore, virtual uniform interstitial experiments were applied to evaluate the advantage of EUD. Results All three plans showed consistent conformity index. Compared with the HIPO plans, the average D2cm³ of bladder, rectum and intestine in the EUD plans were decreased by 0.22 Gy, 0.23 Gy and 0.28 Gy, and those in the h-EUD plans were declined by 0.16 Gy, 0.22 Gy and 0.24 Gy, respectively. The average EUD of bladder, rectum and intestine in the EUD plans were decreased by 0.14 Gy, 0.20 Gy and 0.15 Gy, and those in the h-EUD plans were declined by 0.20 Gy, 0.13 Gy and 0.16 Gy, respectively (all P<0.05). The virtual interstitialexperiment showed EUD could significantly improve the dose sparing for organs at risk (OARs). Conclusion The application of EUD can significantly improve the dose sparing for normal tissues without compromising dose homogeneity and conformity during combined-BT for cervical cancer.