Simeonova-Chergou Anna, Jahnke Anika, Siebenlist Kerstin, Stieler Florian, Mai Sabine, Boda-Heggemann Judit, Wenz Frederik, Lohr Frank, Jahnke Lennart
Department of Radiotherapy and Oncology, University Medical Center Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.
Strahlenther Onkol. 2016 Mar;192(3):166-73. doi: 10.1007/s00066-015-0934-z. Epub 2016 Jan 15.
High-dose radiotherapy of lung cancer is challenging. Tumors may move by up to 2 cm in craniocaudal and anteroposterior directions as a function of breathing cycle. Tumor displacement increases with treatment time, which consequentially increases the treatment uncertainty.
This study analyzed whether automatically gated cone-beam-CT (CBCT)-controlled intensity modulated fast deep inspiration breath hold (DIBH) stereotactic body radiation therapy (SBRT) in flattening filter free (FFF) technique and normofractionated lung DIBH intensity-modulated radiotherapy (IMRT)/volumetric-modulated arc therapy (VMAT) treatments delivered with a flattening filter can be applied with sufficient accuracy within a clinically acceptable timeslot.
Plans of 34 patients with lung tumors were analyzed. Of these patients, 17 received computer-controlled fast DIBH SBRT with a dose of 60 Gy (5 fractions of 12 Gy or 12 fractions of 5 Gy) in an FFF VMAT technique (FFF-SBRT) every other day and 17 received conventional VMAT with a flattening filter (conv-VMAT) and 2-Gy daily fractional doses (cumulative dose 50-70 Gy).
FFF-SBRT plans required more monitor units (MU) than conv-VMAT plans (2956.6 ± 885.3 MU for 12 Gy/fraction and 1148.7 ± 289.2 MU for 5 Gy/fraction vs. 608.4 ± 157.5 MU for 2 Gy/fraction). Total treatment and net beam-on times were shorter for FFF-SBRT plans than conv-VMAT plans (268.0 ± 74.4 s vs. 330.2 ± 93.6 s and 85.8 ± 25.3 s vs. 117.2 ± 29.6 s, respectively). Total slot time was 13.0 min for FFF-SBRT and 14.0 min for conv-VMAT. All modalities could be delivered accurately despite multiple beam-on/-off cycles and were robust against multiple interruptions.
Automatically gated CBCT-controlled fast DIBH SBRT in VMAT FFF technique and normofractionated lung DIBH VMAT can be applied with a low number of breath-holds in a short timeslot, with excellent dosimetric accuracy. In clinical routine, these approaches combine optimally reduced lung tissue irradiation with maximal delivery precision for patients with small and larger lung tumors.
肺癌的高剂量放射治疗具有挑战性。肿瘤可能会根据呼吸周期在头脚方向和前后方向移动多达2厘米。肿瘤位移随治疗时间增加，这相应地增加了治疗的不确定性。
本研究分析了在无均整器（FFF）技术下自动门控锥形束CT（CBCT）控制的强度调制快速深吸气屏气（DIBH）立体定向体部放射治疗（SBRT）以及使用均整器进行的常规分割肺DIBH强度调制放射治疗（IMRT）/容积调强弧形治疗（VMAT）是否能在临床可接受的时间范围内以足够的精度应用。
分析了34例肺肿瘤患者的计划。其中，17例患者每隔一天接受FFF VMAT技术（FFF-SBRT）的计算机控制快速DIBH SBRT，剂量为60 Gy（5次分割，每次12 Gy或12次分割，每次5 Gy），17例患者接受带有均整器的常规VMAT（conv-VMAT），每日分次剂量为2 Gy（累积剂量50 - 70 Gy）。
FFF-SBRT计划所需的监测单位（MU）比conv-VMAT计划更多（每次分割12 Gy时为2956.6±885.3 MU，每次分割5 Gy时为1148.7±289.2 MU，而每次分割2 Gy时为608.4±157.5 MU）。FFF-SBRT计划的总治疗时间和净束流开启时间比conv-VMAT计划短（分别为268.0±74.4秒对330.2±93.6秒和85.8±25.3秒对117.2±29.6秒）。FFF-SBRT的总时段时间为13.0分钟，conv-VMAT为14.0分钟。尽管有多个束流开启/关闭周期，但所有模式都能准确实施，并且对多次中断具有鲁棒性。
在VMAT FFF技术下自动门控CBCT控制的快速DIBH SBRT以及常规分割肺DIBH VMAT可在短时间内以较少的屏气次数应用，剂量学精度优异。在临床常规中，这些方法能将对肺组织的照射降至最优，同时为大小不同的肺肿瘤患者提供最大的递送精度。
