Department of Radiation Oncology, Catharina Hospital, Eindhoven, The Netherlands; Department of Radiation Oncology, The Netherland Cancer Institute, Amsterdam, The Netherlands.
Department of Quality Assurance, EORTC Headquarters, Brussels, Belgium.
Radiother Oncol. 2019 Mar;132:63-69. doi: 10.1016/j.radonc.2018.10.025. Epub 2018 Dec 21.
To report on the benchmark case (BC) study performed in the context of the European Organisation for Research and Treatment of Cancer prospective multicentre Lungtech trial of SBRT for patients with inoperable centrally located lung tumours.
Target volume and organs at risk (OARs) delineations first needed to be acceptable before the treatment plan was reviewed. Retrospectively, Dice similarity coefficients of the OARs and the target volumes were calculated and a set of gold standard contours adapted for each institution margins was applied on the accepted dose submissions to evaluate the influence of acceptable delineation variations on dosimetry.
Twenty-five institutions participated. Five BCs were accepted at the first attempt. Twenty institutions had to revise their delineation at least once and seven had to revise their planning once. The V Gy dose coverage improved significantly (p = 0.05) between the first and final submissions from median (range) 94.8% (22.5-97.8) to 95.3% (70.5-99.3). The median Dice coefficient varied significantly between OARs: The lowest values were found for the brachial plexus 0.25 (0.01-0.54) and the highest for the spinal cord 0.89 (0.71-0.95). The mean PTV Dice coefficient was 0.82 (0.48-0.92). Applying the gold standard contours, only one institution remained compliant with the dose coverage criteria with V Gy median (range) of 83.4% (54.2-93.9).
Clinical guidelines and radiotherapy protocols are not a substitute for timely radiotherapy quality assurance procedures, which improve dose coverage significantly. Delineation remains the main source of BC rejection and plan review without first reviewing delineation may not be efficient. Our results show that delineation variations seem to have a larger influence on PTV coverage than variations in planning and irradiation techniques and thus suggest that dose tolerance criteria should preferably take into account the accuracy of delineation.
报告在欧洲癌症研究与治疗组织前瞻性多中心 Lungtech 立体定向放疗（SBRT）不可切除中央型肺癌患者试验的背景下进行的基准病例（BC）研究。
在审查治疗计划之前，首先需要接受靶区和危及器官（OARs）的勾画。回顾性地，计算了 OAR 和靶区的 Dice 相似系数，并在接受的剂量提交中应用了一套适用于每个机构的金标准轮廓，以评估可接受勾画变化对剂量学的影响。
25 个机构参与。第一次尝试接受了 5 个 BC。20 个机构至少需要修改一次勾画，7 个机构需要修改一次计划。Gy 剂量覆盖率从第一次和最后一次提交的中位数（范围）94.8%（22.5-97.8）显著提高到 95.3%（70.5-99.3）（p=0.05）。OAR 之间的 Dice 系数差异显著：最低值为臂丛 0.25（0.01-0.54），最高值为脊髓 0.89（0.71-0.95）。PTV 的平均 Dice 系数为 0.82（0.48-0.92）。应用金标准轮廓，只有一个机构仍符合剂量覆盖率标准，中位 V Gy（范围）为 83.4%（54.2-93.9）。
临床指南和放射治疗方案不能替代及时的放射治疗质量保证程序，后者可显著提高剂量覆盖率。勾画仍然是 BC 拒绝和计划审查的主要原因，如果不首先审查勾画，可能效率不高。我们的结果表明，勾画变化对 PTV 覆盖率的影响似乎大于计划和照射技术的变化，因此建议剂量耐受标准最好考虑到勾画的准确性。
