Erasmus MC Cancer Institute, Department of Radiation Oncology, Rotterdam, The Netherlands.
Erasmus MC Cancer Institute, Department of Radiation Oncology, Rotterdam, The Netherlands; Delft University of Technology, Faculty of Applied Sciences, Section Radiation Detection and Medical Imaging, The Netherlands.
Radiother Oncol. 2016 Jul;120(1):56-62. doi: 10.1016/j.radonc.2016.04.038. Epub 2016 May 10.
To quantify the impact of the degree of robustness against setup errors and range errors on organ-at-risk (OAR) dose and normal tissue complication probabilities (NTCPs) in intensity-modulated proton therapy for oropharyngeal cancer patients.
For 20 oropharyngeal cases (10 unilateral and 10 bilateral), robust treatment plans were generated using 'minimax' worst-case optimization. We varied the robustness against setup errors ('setup robustness') from 1 to 7mm and the robustness against range errors ('range robustness') from 1% to 7% (+1mm). We evaluated OAR doses and NTCP-values for xerostomia, dysphagia and larynx edema.
Varying the degree of setup robustness was found to have a considerably larger impact than varying the range robustness. Increasing setup robustness from 1mm to 3, 5, and 7mm resulted in average NTCP-values to increase by 1.9, 4.4 and 7.5 percentage point, whereas they increased by only 0.4, 0.8 and 1.2 percentage point when increasing range robustness from 1% to 3%, 5% and 7%. The degree of setup robustness was observed to have a clinically significant impact in bilateral cases in particular.
For oropharyngeal cancer patients, minimizing setup errors should be given a higher priority than minimizing range errors.
量化在针对口咽癌患者的调强质子治疗中，针对摆位误差和射程误差的稳健程度对危及器官（OAR）剂量和正常组织并发症概率（NTCP）的影响。
针对 20 例口咽癌病例（10 例单侧，10 例双侧），使用“最小最大”最坏情况优化生成稳健的治疗计划。我们将针对摆位误差的稳健程度（“摆位稳健性”）从 1mm 变化到 7mm，将针对射程误差的稳健程度（“射程稳健性”）从 1%变化到 7%（+1mm）。我们评估了口干、吞咽困难和喉水肿的 OAR 剂量和 NTCP 值。
与改变射程稳健性相比，改变摆位稳健性对结果的影响要大得多。将摆位稳健性从 1mm 增加到 3mm、5mm 和 7mm，平均 NTCP 值分别增加 1.9、4.4 和 7.5 个百分点，而将射程稳健性从 1%增加到 3%、5%和 7%时，平均 NTCP 值仅分别增加 0.4、0.8 和 1.2 个百分点。在双侧病例中，摆位稳健性的程度观察到具有显著的临床影响。
对于口咽癌患者，应优先考虑最小化摆位误差，而不是最小化射程误差。
