On-line adaptive MR guided radiotherapy for locally advanced pancreatic cancer: Clinical and dosimetric considerations.
On-line adaptive MR guided radiotherapy for locally advanced pancreatic cancer: Clinical and dosimetric considerations.
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DOI：
10.1016/j.tipsro.2020.06.001
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发表时间：
2020-09-01
影响因子：
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通讯作者：
Valentini, Vincenzo
中科院分区：
文献类型：
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作者：
Placidi, Lorenzo;Romano, Angela;Valentini, Vincenzo
简介：磁共振引导放射治疗（MRgRT）允许治疗计划的在线调整（OA），以优化基于患者解剖结构的每日剂量分布，就在分次输送之前。本研究的目的是评估在我们机构针对局部晚期胰腺癌（LAPC）患者实施的OA工作流程的可行性和剂量学改进，包括靶区覆盖和危及器官（OAR）保留。我们回顾性分析了8例接受MRgRT联合OA入路治疗的LAPC患者，采用电视辅助吸气屏气，共38次，剂量范围为30戈伊~ 40戈伊，分5次进行。基线计划的剂量分布首先根据日常解剖计算，获得“预测”计划以评估剂量测定改善。如果剂量分布不符合计划阶段设定的约束条件，则在距PTV外缘3 cm的距离内重新勾画PTV、GTV和OAR，并生成新的在线“自适应”计划。其他临床和计划参数也进行了评估，以评估的可行性和剂量学的好处在线自适应workflow.RESULTS：出38个总分数，26（68.4%）适应在线和12（31.6%）使用基线计划交付。自适应工作流程的使用在我们的临床实践中是可行的，并且对所有患者都有利：平均PTV V95%增加了10.8%（5.7-20.8），而平均CTV V98%增加了12.6%（7.3-17.7）。OARs V33和V25也显示出积极的趋势，避免不必要的辐射。结论：OA工作流程提高了MRgRT的剂量学效益，防止了OARs高剂量的发生，提高了LAPC立体定向治疗的安全性，对我们的日常临床实践没有任何缺点。
INTRODUCTION: Magnetic Resonance-guided Radiation Therapy (MRgRT) allows online adaptations (OA) of the treatment plan to optimize daily dose distribution based on patient's anatomy, just before fraction delivery. The aim of this study is to evaluate feasibility and the dosimetric improvement of the OA workflow implemented in our institution for locally advanced pancreatic cancer (LAPC) patients, in terms of target coverage and organs at risk (OARs) sparing.METHODS: We retrospectively analysed 8 LAPC patients treated with MRgRT in combination with the OA approach, using video-assisted inspiratory breath-hold for a total of 38 fractions with a dose ranging from 30 Gy to 40 Gy in 5 fractions.Dose distribution of the baseline plan was first calculated based on daily anatomy, obtaining a "predicted" plan to assess the dosimetric improvement. If the dose distribution did not meet the constraints set in the planning phase, PTV, GTV and OARs were re-contoured within a distance of 3 cm from the PTV external edge and a new online "adaptive" plan was generated. Other clinical and planning parameters were also evaluated to assess the feasibility and the dosimetic benefit of the online adaptive workflow.RESULTS: Out of 38 total fractions, 26 (68.4%) were adapted online and 12 (31.6%) were delivered using the baseline plan. The use of the adaptive workflow resulted to be feasible in our clinical practice and advantageous in all the patients: mean PTV V95% increased by 10.8% (5.7-20.8) while mean CTV V98% of 12.6% (7.3-17.7). Also OARs V33 and V25 showed a positive trend avoiding unnecessary irradiation.CONCLUSION: OA workflow improves the dosimetric benefit of MRgRT, preventing the occurrence of high-doses to OARs and increasing the safety of stereotactic treatment for LAPC, without any drawback for our daily clinical practice routine.