Mihailidis Dimitris N, Plants Brian, Farinash Lloyd, Harmon Michael, Whaley Lewis, Raja Prem, Tomara Pelagia
Charleston Radiation Therapy Consultants, Charleston, WV, USA.
Med Dosim. 2010 Spring;35(1):67-76. doi: 10.1016/j.meddos.2009.03.002. Epub 2009 Apr 14.
We investigate whether IMRT optimization based on generalized equivalent uniform dose (gEUD) objectives for organs at risk (OAR) results in superior dosimetric outcomes when compared with multiple dose-volume (DV)-based objectives plans for patients with intact breast and postmastectomy chest wall (CW) cancer. Four separate IMRT plans were prepared for each of the breast and CW cases (10 patients). The first three plans used our standard in-house, physician-selected, DV objectives (phys-plan); gEUD-based objectives for the OARs (gEUD-plan); and multiple, "very stringent," DV objectives for each OAR and PTV (DV-plan), respectively. The fourth plan was only beam-fluence optimized (FO-plan), without segmentation, which used the same objectives as in the DV-plan. The latter plan was to be used as an "optimum" benchmark without the effects of the segmentation for deliverability. Dosimetric quantities, such as V(20Gy) for the ipsilateral lung and mean dose (D(mean)) for heart, contralateral breast, and contralateral lung were used to evaluate the results. For all patients in this study, we have seen that the gEUD-based plans allow greater sparing of the OARs while maintaining equivalent target coverage. The average ipsilateral lung V(20Gy) reduced from 22 +/- 4.4% for the FO-plan to 18 +/- 3% for the gEUD-plan. All other dosimetric quantities shifted towards lower doses for the gEUD-plan. gEUD-based optimization can be used to search for plans of different DVHs with the same gEUDs. The use of gEUD allows selective optimization and reduction of the dose for each OAR and results in a truly individualized treatment plan.
我们研究了对于完整乳房和乳房切除术后胸壁（CW）癌患者，基于危及器官（OAR）的广义等效均匀剂量（gEUD）目标进行调强放疗（IMRT）优化，与基于多个剂量体积（DV）目标的计划相比，是否能产生更优的剂量学结果。为每个乳房和CW病例（10名患者）分别准备了4个独立的IMRT计划。前三个计划分别使用我们内部标准的、医生选择的DV目标（物理计划）；基于OAR的gEUD目标（gEUD计划）；以及针对每个OAR和计划靶体积（PTV）的多个“非常严格的”DV目标（DV计划）。第四个计划仅进行射束流强优化（FO计划），不进行分割，其使用与DV计划相同的目标。后一个计划将用作“最佳”基准，不考虑分割对可交付性的影响。使用诸如同侧肺的V（20Gy）以及心脏、对侧乳房和对侧肺的平均剂量（D（mean））等剂量学量来评估结果。在本研究的所有患者中，我们发现基于gEUD的计划在保持等效靶区覆盖的同时，能更大程度地保护OAR。同侧肺的平均V（20Gy）从FO计划的22±4.4%降至gEUD计划的18±3%。对于gEUD计划，所有其他剂量学量都向更低剂量偏移。基于gEUD的优化可用于搜索具有相同gEUD的不同剂量体积直方图（DVH）的计划。使用gEUD可对每个OAR进行选择性优化并降低剂量，从而产生真正个体化的治疗计划。
