Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota, USA.
College of Engineering, Department of Biomedical Engineering, The University of Iowa, Iowa City, IA, USA.
J Appl Clin Med Phys. 2018 Mar;19(2):83-92. doi: 10.1002/acm2.12247. Epub 2018 Jan 19.
The objective of this study was to assess the recommended DVH parameter (e.g., D2 cc) addition method used for combining EBRT and HDR plans, against a reference dataset generated from an EQD2-based DVH addition method. A revised DVH parameter addition method using EBRT DVH parameters derived from each patient's plan was proposed and also compared with the reference dataset. Thirty-one biopsy-proven cervical cancer patients who received EBRT and HDR brachytherapy were retrospectively analyzed. A parametrial and/or paraaortic EBRT boost were clinically performed on 13 patients. Ten IMRT and 21 3DCRT plans were determined. Two different HDR techniques for each HDR plan were analyzed. Overall D2 cc and D0.1 cc OAR doses in EQD2 were statistically analyzed for three different DVH parameter addition methods: a currently recommended method, a proposed revised method, and a reference DVH addition method. The overall D2 cc values for all rectum, bladder, and sigmoid for a conformal, volume optimization HDR plan generated using the current DVH parameter addition method were significantly underestimated on average -5 to -8% when compared to the values obtained from the reference DVH addition technique (P < 0.01). The revised DVH parameter addition method did not present statistical differences with the reference technique (P > 0.099). When PM boosts were considered, there was an even greater average underestimation of -8~-10% for overall OAR doses of conformal HDR plans when using the current DVH parameter addition technique as compared to the revised DVH parameter addition. No statistically significant differences were found between the 3DCRT and IMRT techniques (P > 0.3148). It is recommended that the overall D2 cc EBRT doses are obtained from each patient's EBRT plan.
本研究旨在评估将 EBRT 和 HDR 计划相结合时使用的推荐剂量体积直方图（DVH）参数（例如，D2 cc）添加方法，与基于 EQD2 的 DVH 添加方法生成的参考数据集进行比较。提出了一种使用从每位患者计划中得出的 EBRT DVH 参数的修订 DVH 参数添加方法，并与参考数据集进行了比较。回顾性分析了 31 例经活检证实的宫颈癌患者，这些患者接受了 EBRT 和 HDR 近距离放疗。对 13 例患者进行了临床宫旁和/或腹主动脉旁 EBRT 加量。确定了 10 个调强放疗和 21 个 3DCRT 计划。分析了每个 HDR 计划的两种不同的 HDR 技术。在三种不同的 DVH 参数添加方法中，对 EQD2 中的总 D2 cc 和 OAR 剂量的 D0.1 cc 进行了统计分析：一种是当前推荐的方法，一种是建议的修订方法，还有一种是参考的 DVH 添加方法。与参考的 DVH 添加技术相比，当前的 DVH 参数添加方法生成的适形、体积优化 HDR 计划的所有直肠、膀胱和乙状结肠的总 D2 cc 值平均低估了 5%至 8%（P < 0.01）。修订后的 DVH 参数添加方法与参考技术无统计学差异（P > 0.099）。当考虑 PM 加量时，与修订后的 DVH 参数添加相比，使用当前的 DVH 参数添加技术，适形 HDR 计划的 OAR 总剂量的平均低估幅度更大，为 -8%至 -10%。3DCRT 和 IMRT 技术之间没有发现统计学上的显著差异（P > 0.3148）。建议从每位患者的 EBRT 计划中获取总 D2 cc EBRT 剂量。
