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Abstract：
UNASSIGNED: Dynamic trajectory radiotherapy (DTRT) has been shown to improve healthy tissue sparing compared to volumetric arc therapy (VMAT). This study aimed to assess and compare the robustness of DTRT and VMAT treatment-plans for head and neck (H&N) cancer to patient-setup (PS) and machine-positioning uncertainties.
UNASSIGNED: The robustness of DTRT and VMAT plans previously created for 46 H&N cases, prescribed 50-70 Gy to 95 % of the planning-target-volume, was assessed. For this purpose, dose distributions were recalculated using Monte Carlo, including uncertainties in PS (translation and rotation) and machine-positioning (gantry-, table-, collimator-rotation and multi-leaf collimator (MLC)). Plan robustness was evaluated by the uncertainties\' impact on normal tissue complication probabilities (NTCP) for xerostomia and dysphagia and on dose-volume endpoints. Differences between DTRT and VMAT plan robustness were compared using Wilcoxon matched-pair signed-rank test (α = 5 %).
UNASSIGNED: Average NTCP for moderate-to-severe xerostomia and grade ≥ II dysphagia was lower for DTRT than VMAT in the nominal scenario (0.5 %, p = 0.01; 2.1 %, p < 0.01) and for all investigated uncertainties, except MLC positioning, where the difference was not significant. Average differences compared to the nominal scenario were ≤ 3.5 Gy for rotational PS (≤ 3°) and machine-positioning (≤ 2°) uncertainties, <7 Gy for translational PS uncertainties (≤ 5 mm) and < 20 Gy for MLC-positioning uncertainties (≤ 5 mm).
UNASSIGNED: DTRT and VMAT plan robustness to the investigated uncertainties depended on uncertainty direction and location of the structure-of-interest to the target. NTCP remained on average lower for DTRT than VMAT even when considering uncertainties.
UNASSIGNED: The robustness of DTRT and VMAT plans previously created for 46 H&N cases, prescribed 50-70 Gy to 95 % of the planning-target-volume, was assessed. For this purpose, dose distributions were recalculated using Monte Carlo, including uncertainties in PS (translation and rotation) and machine-positioning (gantry-, table-, collimator-rotation and multi-leaf collimator (MLC)). Plan robustness was evaluated by the uncertainties\' impact on normal tissue complication probabilities (NTCP) for xerostomia and dysphagia and on dose-volume endpoints. Differences between DTRT and VMAT plan robustness were compared using Wilcoxon matched-pair signed-rank test (α = 5 %).
UNASSIGNED: Average NTCP for moderate-to-severe xerostomia and grade ≥ II dysphagia was lower for DTRT than VMAT in the nominal scenario (0.5 %, p = 0.01; 2.1 %, p < 0.01) and for all investigated uncertainties, except MLC positioning, where the difference was not significant. Average differences compared to the nominal scenario were ≤ 3.5 Gy for rotational PS (≤ 3°) and machine-positioning (≤ 2°) uncertainties, <7 Gy for translational PS uncertainties (≤ 5 mm) and < 20 Gy for MLC-positioning uncertainties (≤ 5 mm).
UNASSIGNED: DTRT and VMAT plan robustness to the investigated uncertainties depended on uncertainty direction and location of the structure-of-interest to the target. NTCP remained on average lower for DTRT than VMAT even when considering uncertainties.
摘要：
■与体积电弧疗法（VMAT）相比，动态轨迹放射治疗（DTRT）已被证明可以改善健康组织的保护。这项研究旨在评估和比较头颈部（H＆N）癌症的DTRT和VMAT治疗计划对患者设置（PS）和机器定位不确定性的鲁棒性。
■以前为46个H&N案例创建的DTRT和VMAT计划的稳健性，规定50-70Gy至计划目标量的95%，被评估。为此,使用蒙特卡罗重新计算剂量分布，包括PS(平移和旋转)和机器定位(gantry-，表-,准直器旋转和多叶准直器（MLC））。通过不确定因素对口干症和吞咽困难的正常组织并发症概率（NTCP）和剂量体积终点的影响来评估计划的稳健性。使用Wilcoxon配对符号秩检验(α=5%)比较DTRT和VMAT计划稳健性之间的差异。
■在名义情况下，中度至重度口干症和≥II级吞咽困难的平均NTCP低于VMAT（0.5％，p=0.01；2.1%，p<0.01)，对于所有调查的不确定性，除了MLC定位，差异不显著。对于旋转PS(≤3°)和机器定位(≤2°)不确定性，与标称情况相比的平均差异≤3.5Gy，对于平移PS不确定性（≤5mm），<7Gy，对于MLC定位不确定性（≤5mm），<20Gy。
■DTRT和VMAT计划对所研究的不确定性的鲁棒性取决于目标感兴趣结构的不确定性方向和位置。即使考虑到不确定性，DTRT的NTCP平均仍低于VMAT。
■以前为46个H&N案例创建的DTRT和VMAT计划的稳健性，规定50-70Gy至计划目标量的95%，被评估。为此,使用蒙特卡罗重新计算剂量分布，包括PS(平移和旋转)和机器定位(gantry-，表-,准直器旋转和多叶准直器（MLC））。通过不确定因素对口干症和吞咽困难的正常组织并发症概率（NTCP）和剂量体积终点的影响来评估计划的稳健性。使用Wilcoxon配对符号秩检验(α=5%)比较DTRT和VMAT计划稳健性之间的差异。
■在名义情况下，中度至重度口干症和≥II级吞咽困难的平均NTCP低于VMAT（0.5％，p=0.01；2.1%，p<0.01)，对于所有调查的不确定性，除了MLC定位，差异不显著。对于旋转PS(≤3°)和机器定位(≤2°)不确定性，与标称情况相比的平均差异≤3.5Gy，对于平移PS不确定性（≤5mm），<7Gy，对于MLC定位不确定性（≤5mm），<20Gy。
■DTRT和VMAT计划对所研究的不确定性的鲁棒性取决于目标感兴趣结构的不确定性方向和位置。即使考虑到不确定性，DTRT的NTCP平均仍低于VMAT。
