Borm Kai J, Hofmann Christopher, Düsberg Mathias, Oechsner Markus, Dapper Hendrik, Devecka Michal, Combs Stephanie E
Department of Radiation Oncology, Klinikum rechts der Isar, Technical University of Munich (TUM), Ismaninger Straße 22, 81675 Munich, Germany.
Deutsches Konsortium für Translationale Krebsforschung (DKTK), Partner Site Munich, 81675 Munich, Germany.
Cancers (Basel). 2021 Apr 18;13(8):1951. doi: 10.3390/cancers13081951.
The current study aims to determine whether exclusion of lung tissue from planning treatment volume (PTV) is a valid organ at risk (OAR)-sparing technique during internal mammary irradiation (IMNI). Twenty patients with left-sided breast cancer undergoing adjuvant radiotherapy including IMNI after mastectomy or lumpectomy with daily ConeBeam CT (CBCT; median n = 28) were enrolled in the current study. The daily dose distribution of the patients was estimated by recalculating treatment plans on CBCT-scans based on a standard PTV (PTV margin: 5mm-STD) and a modified PTV, which excluded overlapping lung tissue (ExLung). Using 3D-deformable dose accumulation, the dose coverage in the target volume was estimated in dependence of the PTV-margins. The estimated delivered dose in the IMN-CTV was significantly lower for the ExLung PTV compared to the STD PTV: ExLung: V95%: 76.6 ± 22.9%; V90%: 89.6 ± 13.2%, STD: V95%: 95.6 ± 7.4%; V90%: 99.1 ± 2.7%. Daily CBCT imaging cannot sufficiently compensate the anatomic changes and intrafraction movement throughout the treatment. Therefore, to ensure adequate delivery of the prescribed dose to the IMN-CTV, exclusion of lung tissue from the PTV to spare the OARs is not recommended.
本研究旨在确定在乳腺内照射（IMNI）期间，将肺组织排除在计划靶体积（PTV）之外是否是一种有效的危及器官（OAR）保护技术。本研究纳入了20例左侧乳腺癌患者，这些患者在乳房切除或肿块切除术后接受包括IMNI在内的辅助放疗，每日进行锥形束CT（CBCT；中位数n = 28）扫描。通过基于标准PTV（PTV边界：5mm-STD）和排除重叠肺组织的改良PTV（ExLung）在CBCT扫描上重新计算治疗计划，来估计患者的每日剂量分布。使用3D可变形剂量累积，根据PTV边界估计靶体积内的剂量覆盖情况。与STD PTV相比，ExLung PTV在IMN-CTV中的估计输送剂量显著更低：ExLung：V95%：76.6±22.9%；V90%：89.6±13.2%，STD：V95%：95.6±7.4%；V90%：99.1±2.7%。每日CBCT成像无法充分补偿整个治疗过程中的解剖变化和分次内运动。因此，为确保向IMN-CTV充分输送规定剂量，不建议将肺组织从PTV中排除以保护OARs。
