Institute of Radiation Protection, Helmholtz Zentrum München Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.
Klinik und Poliklinik für Strahlentherapie, MVZ der Universitätsmedizin Rostock am Standort Südstadt gGmbH, Universitätsmedizin Rostock, Südring 75, 18059, Rostock, Germany.
Strahlenther Onkol. 2019 Jan;195(1):32-42. doi: 10.1007/s00066-018-1384-1. Epub 2018 Oct 22.
With the ever-increasing cure rates in breast cancer, radiotherapy-induced cancers have become an important issue. This study aimed to estimate secondary cancer risks for different treatment techniques, taking into account organs throughout the body.
Organ doses were evaluated for a tangential three-dimensional conformal (3D-CRT) and a multi-field intensity-modulated radiotherapy (IMRT) plan using a validated, Monte Carlo-based treatment planning system. Effects of wedges and of forward versus inverse planning were systematically investigated on the basis of phantom measurements. Organ-specific cancer risks were estimated using risk coefficients derived from radiotherapy patients or from the atomic bomb survivors.
In the 3D-CRT plan, mean organ doses could be kept below 1 Gy for more remote organs than the lung, heart, and contralateral breast, and decreased to a few cGy for organs in the lower torso. Multi-field IMRT led to considerably higher mean doses in organs at risk, the difference being higher than 50% for many organs. Likewise, the peripheral radiation burden was increased by external wedges. No difference was observed for forward versus inverse planning. Despite the lower doses, the total estimated secondary cancer risk in more remote organs was comparable to that in the lung or the contralateral breast. For multi-field IMRT it was 75% higher than for 3D-CRT without external wedges.
Remote organs are important for assessment of radiation-induced cancer risk. Remote doses can be reduced effectively by application of a tangential field configuration and a linear accelerator set-up with low head scatter radiation.
随着乳腺癌治愈率的不断提高，放疗相关性癌症已成为一个重要问题。本研究旨在评估不同治疗技术的继发癌症风险，同时考虑全身各器官。
使用验证的基于蒙特卡罗的治疗计划系统，对切线三维适形（3D-CRT）和多野强度调制放疗（IMRT）计划进行了器官剂量评估。基于体模测量，系统研究了楔形和正向与逆向计划的影响。利用来自放疗患者或原子弹幸存者的风险系数，估算了特定器官的癌症风险。
在 3D-CRT 计划中，对于肺、心脏和对侧乳房以外的远程器官，平均器官剂量可以保持在 1Gy 以下，对于下躯干的器官，则降低至几 cGy。多野 IMRT 导致危险器官的平均剂量显著增加，对于许多器官，差异超过 50%。同样，外部楔形会增加外周辐射负担。正向与逆向计划之间未观察到差异。尽管剂量较低，但在远程器官中，估计的继发癌症总风险与肺或对侧乳房相当。对于多野 IMRT，如果不使用外部楔形，其风险比 3D-CRT 高 75%。
远程器官对于评估辐射诱导癌症风险很重要。通过应用切线野配置和低头部散射辐射的直线加速器设置，可以有效地降低远程器官的剂量。
