Kraus K M, Oechsner M, Wilkens J J, Kessel K A, Münch S, Combs S E
School of Medicine and Klinikum Rechts Der Isar, Department of Radiation Oncology, Technichal University of Munich (TUM), Munich, Germany.
Institute of Radiation Medicine (IRM), Department of Radiation Sciences (DRS), Helmholtz Zentrum München (HMGU), Neuherberg, Germany.
Sci Rep. 2021 Mar 12;11(1):5870. doi: 10.1038/s41598-021-85031-w.
Stereotactic body radiotherapy (SBRT) applies high doses and requires advanced techniques to spare surrounding tissue in the presence of organ motion. In this work patient individual phase gating is investigated. We studied peripheral and central primary lung tumors. The internal target volume (ITV) was defined including different numbers of phases picked from a 4D Computed tomography (CT) defining the gating window (gw). Planning target volume (PTV) reductions depending on the gw were analyzed. A treatment plan was calculated on a reference phase CT (rCT) and the dose for each breathing phase was calculated and accumulated on the rCT. We compared the dosimetric results with the dose calculated when all breathing phases were included for ITV definition. GWs including 1 to 10 breathing phases were analyzed. We found PTV reductions up to 38.4%. The mean reduction of the lung volume receiving 20 Gy due to gating was found to be 25.7% for peripheral tumors and 16.7% for central tumors. Gating considerably reduced esophageal doses. However, we found that simple reduction of the gw does not necessarily influence the dose in a clinically relevant range. Thus, we suggest a patient individual definition of the breathing phases included within the gw.
立体定向体部放射治疗（SBRT）需要高剂量且在器官运动时需要先进技术来保护周围组织。在这项工作中，对患者个体的相位门控进行了研究。我们研究了周围型和中央型原发性肺癌。内部靶区体积（ITV）的定义包括从定义门控窗口（gw）的4D计算机断层扫描（CT）中选取的不同数量的相位。分析了计划靶区体积（PTV）根据gw的减少情况。在参考相位CT（rCT）上计算治疗计划，并在rCT上计算并累积每个呼吸相位的剂量。我们将剂量学结果与在定义ITV时包括所有呼吸相位时计算的剂量进行了比较。分析了包括1至10个呼吸相位的gw。我们发现PTV减少高达38.4%。对于周围型肿瘤，由于门控导致接受20 Gy剂量的肺体积平均减少25.7%，对于中央型肿瘤为16.7%。门控显著降低了食管剂量。然而，我们发现简单减小gw不一定会在临床相关范围内影响剂量。因此，我们建议对gw内包含的呼吸相位进行患者个体定义。
