Dang Thu M, Peters Mitchell J, Hickey Brigid, Semciw Adam
Radiation Oncology Mater Centre, South Brisbane, Queensland, Australia.
School of Health and Rehabilitation Sciences, The University of Queensland, St Lucia, Queensland, Australia.
J Med Imaging Radiat Oncol. 2017 Jun;61(3):379-387. doi: 10.1111/1754-9485.12583. Epub 2017 Jan 24.
A linear accelerator with the flattening-filter removed generates a non-uniform dose profile beam. We aimed to analyse and compare plan quality and treatment time between flattened beam (FB) and flattening-filter-free (FFF) beam to assess the efficacy of FFF beam for stereotactic body radiation therapy (SBRT). The search strategy was based around 3 concepts; radiation therapy, flattening-filter-free and treatment delivery. The years searched were restricted from 2010 to date of review (October 2015). All plan quality comparisons were between FFF and FB plans from the same data sets. We identified 210 potential studies based on the three searched concepts. All articles were screened by two authors for title and abstract and by three authors for full text. Ten studies met the eligibility criteria. Plan quality was evaluated using conformity index (CI), heterogeneity index (HI) and gradient index (GI). Dose to organs-at-risk (OAR) and healthy tissues were compared. Differences between beam-on-time (BOT) and treatment time (T × T) were also analysed. Normalized percentage ratios of CI and HI demonstrated no clinical differences among the studied articles. GI displayed small variations between the articles favouring FFF beam. The BOT with FFF is substantially reduced, and appears to impact the frequency of intra-fraction imaging which, in turn, affects total treatment time. Based on planning tumour volume (PTV) coverage, dose to OAR and healthy tissue sparing, FFF beam is clinically effective for the treatment of cancer patients using SBRT. We recommend the use of FFF beam for SBRT based on these factors and the reported overall treatment time reduction.
去除 flattening 滤波器的直线加速器会产生剂量分布不均匀的射束。我们旨在分析和比较扁平射束（FB）和无 flattening 滤波器射束（FFF）之间的计划质量和治疗时间，以评估 FFF 射束在立体定向体部放射治疗（SBRT）中的疗效。检索策略基于三个概念：放射治疗、无 flattening 滤波器和治疗实施。检索年份限制在 2010 年至综述日期（2015 年 10 月）。所有计划质量比较均在来自相同数据集的 FFF 和 FB 计划之间进行。基于这三个检索概念，我们识别出 210 项潜在研究。所有文章均由两名作者筛选标题和摘要，由三名作者筛选全文。十项研究符合纳入标准。使用适形指数（CI）、异质性指数（HI）和梯度指数（GI）评估计划质量。比较了危及器官（OAR）和健康组织的剂量。还分析了照射时间（BOT）和治疗时间（T×T）之间的差异。CI 和 HI 的标准化百分比比值在各研究文章之间未显示出临床差异。文章之间 GI 显示出有利于 FFF 射束的微小差异。FFF 的 BOT 大幅减少，并且似乎影响了分次内成像的频率，进而影响总治疗时间。基于计划靶体积（PTV）覆盖、OAR 剂量和健康组织保护，FFF 射束在使用 SBRT 治疗癌症患者方面具有临床有效性。基于这些因素以及报道的总体治疗时间减少，我们建议在 SBRT 中使用 FFF 射束。
