Department of Oncology, Lillebaelt Hospital, University Hospital of Southern Denmark, Vejle, Denmark; Institute for Regional Health Research, University of Southern Denmark, Odense M, Denmark.
Department of Oncology, Lillebaelt Hospital, University Hospital of Southern Denmark, Vejle, Denmark.
Acta Oncol. 2024 Jun 20;63:448-455. doi: 10.2340/1651-226X.2024.40049.
Robust optimization has been suggested as an approach to reduce the irradiated volume in lung Stereotactic Body Radiation Therapy (SBRT). We performed a retrospective planning study to investigate the potential benefits over Planning Target Volume (PTV)-based planning.
Thirty-nine patients had additional plans using robust optimization with 5-mm isocenter shifts of the Gross Tumor Volume (GTV) created in addition to the PTV-based plan used for treatment. The optimization included the mid-position phase and the extreme breathing phases of the 4D-CT planning scan. The plans were compared for tumor coverage, isodose volumes, and doses to Organs At Risk (OAR). Additionally, we evaluated both plans with respect to observed tumor motion using the peak tumor motion seen on the planning scan and cone-beam CTs.
Statistically significant reductions in irradiated isodose volumes and doses to OAR were achieved with robust optimization, while preserving tumor dose. The reductions were largest for the low-dose volumes and reductions up to 188 ccm was observed. The robust evaluation based on observed peak tumor motion showed comparable target doses between the two planning methods. Accumulated mean GTV-dose was increased by a median of 4.46 Gy and a non-significant increase of 100 Monitor Units (MU) was seen in the robust optimized plans.
The robust plans required more time to prepare, and while it might not be a feasible planning strategy for all lung SBRT patients, we suggest it might be useful for selected patients.
稳健优化被认为是一种减少肺部立体定向体部放射治疗（SBRT）中照射体积的方法。我们进行了一项回顾性计划研究，以调查与基于计划靶区（PTV）的计划相比的潜在益处。
39 名患者接受了额外的计划，除了用于治疗的 PTV 计划外，还使用稳健优化创建了 5mm 等中心偏移的大体肿瘤体积（GTV）。优化包括 4D-CT 计划扫描的中位置相和极端呼吸相。比较了肿瘤覆盖、等剂量体积和危及器官（OAR）剂量的计划。此外，我们还根据计划扫描和锥形束 CT 上观察到的肿瘤运动，评估了两种计划。
稳健优化实现了照射等剂量体积和 OAR 剂量的显著降低，同时保持了肿瘤剂量。低剂量体积的降低最大，观察到的降低高达 188ccm。基于观察到的峰值肿瘤运动的稳健评估表明，两种计划方法的靶区剂量相当。累积平均 GTV 剂量增加了 4.46Gy，稳健优化计划的 100 个监测单位（MU）增加了 100MU。
稳健的计划需要更多的时间来准备，虽然它可能不是所有肺部 SBRT 患者的可行计划策略，但我们建议它可能对某些患者有用。
