Istanbul Basaksehir Cam and Sakura City Hospital, Istanbul, Turkey.
Istanbul Bakirkoy Dr. Sadi Konuk Research and Training Hospital, Istanbul, Turkey.
Med Dosim. 2022;47(2):184-190. doi: 10.1016/j.meddos.2022.02.001. Epub 2022 Mar 8.
The aim of this study was to evaluate various combinations of Equivalent Uniform Dose (EUD) based and Dose Volume based (DV) cost functions in terms of target coverage and organ sparing for Nasopharyngeal CA. Ten patients diagnosed with Nasopharyngeal CA were selected for this retrospective study. Different hybrid VMAT plans, including EUD- and DV-based cost functions, were generated for each patient to determine the optimum combination in terms of organ sparing and target coverage. The generated VMAT plans were evaluated based on physical and biological dose parameters. No statistical difference was observed among all plans in terms of target coverage. The p values were ≥ 0.005 for V95, D, and tumor control probability (TCP). The MU efficiency was maximum (67%), and the number of segments (285 segments) was minimum in Hybrid plan. Hybrid plan showed a significant difference compared to others (p = 0.001) in terms of serial organs. Moreover, the combination of serial and parallel complication models provided better reduction of radiation dose in the parotid glands in Plan-3 (p = 0.001). In this study, better protection was obtained when DVH-based cost functions were defined for targets and a combination of EUD- and DVH-based cost functions were used for OARs.
本研究旨在评估基于等效均匀剂量（EUD）和剂量体积（DV）的成本函数的各种组合，以评估鼻咽癌的靶区覆盖和器官保护。选取 10 例鼻咽癌患者进行回顾性研究。为每位患者生成不同的混合 VMAT 计划，包括基于 EUD 和 DV 的成本函数，以确定在器官保护和靶区覆盖方面的最佳组合。基于物理和生物剂量参数对生成的 VMAT 计划进行评估。所有计划在靶区覆盖方面均无统计学差异。V95、D 和肿瘤控制概率（TCP）的 p 值均≥0.005。MU 效率最高（67%），段数最少（285 段）。与其他计划相比，混合计划在序列器官方面有显著差异（p=0.001）。此外，在计划 3 中，串联和并行并发症模型的组合在腮腺中提供了更好的辐射剂量降低（p=0.001）。在本研究中，当为靶区定义基于剂量体积的成本函数，以及为 OAR 使用基于等效均匀剂量和剂量体积的成本函数组合时，可获得更好的保护。
