Faculty of Medicine, University of Paris-Saclay, Le Kremlin-Bicetre, France.
Department of Radiotherapy, Tenon Hospital, APHP, Sorbonne University, Paris, France.
Cancer Invest. 2022 Nov;40(10):868-878. doi: 10.1080/07357907.2022.2103705. Epub 2022 Jul 24.
The aim of this study is to compare the dose delivered to the organs at risk (OAR), using static beams (SF) and a dynamic conformational arc (DCA) with flattening filter free (FFF) beams, for lung stereotactic body radiation therapy (SBRT).
100 patients with lung cancer were treated with SBRT, using FF beams (TrueBeam STx, 6 MV, IQ = 0.67, 600 MU/min), separated into two groups: DCA (50 patients) and SF (50 patients). These patients were retrospectively re-planned using 6XFFF beams, IQ = 0.63, 1400 MU/min. The beam-on time and dosimetric gain on planning target volume (PTV) and OARs (heart, spinal cord, planning risk volume (PRV) of spinal cord, esophagus, lungs and ribs) were analyzed according to tumor location. The comparison of median values was performed using the non-parametric Wilcoxon test (significance level: < 0.05).
PTV coverage was 98.90% versus 98.40% (DCA) and 98.8% versus 98.3% (SF) for the FF and FFF beams, respectively. The median dosimetric gain to the heart, spinal cord, PRV spinal cord, esophagus and lungs was 6% (4-11%) in the central region and 8% (2-23%) in the peripheral region, using FFF ( < 0.05). The dose received by the ribs decreases by 5-6 Gy, using FFF beams. The median gain in beam-on time ranged from 31% to 34% for SF and from 44 to 52% for DCA using FFF beams.
The FFF beams reduce the dose received by all OARs, regardless of the used technique or tumor location, reducing treatment delivery time as well.
本研究旨在比较使用静态射野（SF）和动态适形弧（DCA）与不带均整滤波器的（FFF）射束对肺部立体定向体部放疗（SBRT）中危及器官（OAR）的剂量分布。
100 例肺癌患者采用 SBRT 治疗，使用 FF 射束（TrueBeam STx，6MV，IQ=0.67，600MU/min），分为两组：DCA（50 例）和 SF（50 例）。这些患者采用 6XFFF 射束（IQ=0.63，1400MU/min）进行回顾性再计划。根据肿瘤位置分析计划靶区（PTV）和 OAR（心脏、脊髓、脊髓计划危险体积（PRV）、食管、肺和肋骨）的射束开启时间和剂量增益。使用非参数 Wilcoxon 检验（显著性水平：<0.05）对中位数进行比较。
FF 和 FFF 射束的 PTV 覆盖率分别为 98.90%和 98.40%（DCA）和 98.8%和 98.3%（SF）。心脏、脊髓、PRV 脊髓、食管和肺的中位剂量增益在中央区为 6%（4-11%），在周边区为 8%（2-23%），使用 FFF 射束（<0.05）。使用 FFF 射束时，肋骨接受的剂量减少 5-6Gy。SF 的中位开启时间增益范围为 31%-34%，DCA 为 44%-52%。
FFF 射束降低了所有 OAR 的剂量，无论使用的技术或肿瘤位置如何，同时也减少了治疗输送时间。
