Dosimetric consequences of intrafraction prostate motion in scanned ion beam radiotherapy
Dosimetric consequences of intrafraction prostate motion in scanned ion beam radiotherapy
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DOI：
10.1016/j.radonc.2014.03.022
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发表时间：
2014-07-01
影响因子：
5.7
通讯作者：
Jelen, Urszula
中科院分区：
文献类型：
--
作者：
Ammazzalorso, Filippo;Graef, Sebastian;Jelen, Urszula
背景与目的：在粒子治疗中，扫描光束与靶运动的相互作用可能导致剂量恶化。碳离子前列腺治疗研究了这种影响的程度和减轻这种影响的可能性。方法和材料：针对12例前列腺病例，采用3种扫描光束设置（光斑尺寸分别为6,7和9mm，栅格间距分别为2,2和3mm）为3种规划边界（3,6和9mm）制备9种碳离子治疗方案。在有和没有光束内运动补偿的情况下，重新计算了5种前列腺运动方案。结果：对于6mm边缘和7mm斑点，纯漂移运动时CTV D-95%变化中值（最大）为-0.2 (-2.6)pp（百分点），瞬时运动时为-3.8 (-6.0)pp和-2.8 (-3.1)pp，混合运动时为-4.8 (-7.7)pp和-1.8 (-5.7)pp。没有特定的栅格设置带来明显的优势，而规划裕度扩展在漂流为主的场景中显示出统计学上显著的效果。波束内运动补偿提高了CTV覆盖率。结论：前列腺运动可导致明显的靶覆盖率下降，这取决于个体的运动模式，只能通过计划-时间对策来部分避免。在可能的发射时间对抗中，波束内运动补偿能够提高目标覆盖。2014爱思唯尔爱尔兰有限公司版权所有。
Background and purpose: Scanned-beam interplay with the intrafraction target motion may result in dose deterioration in particle therapy. The magnitude of this effect and the possibilities to mitigate it were investigated for carbon ion prostate treatments.Methods and materials: For 12 prostate cases, 9 carbon ion treatment plans were prepared using 3 scanned-beam settings (spot sizes of 6, 7 and 9 mm and, respectively, raster pitches of 2, 2 and 3 mm) for 3 planning margins (3, 6 and 9 mm). Plans were recomputed in presence of 5 intrafraction prostate motion scenarios with and without intra-beam motion compensation.Results: For 6 mm margin and 7 mm spot, the median (max) CTV D-95% change was -0.2 (-2.6) pp (percentual points) with pure drift motion, -3.8 (-6.0) pp and -2.8 (-3.1) pp in transient motion scenarios and -4.8 (-7.7) pp and -1.8 (-5.7) pp in mixed motion scenarios. No particular raster setting brought distinct advantage, while planning margin expansion showed statistically significant effects for drift-dominated scenarios. Intra-beam motion compensation yielded improved CTV coverage.Conclusion: Intrafraction prostate motion can lead to marked target coverage deterioration, dependent on individual motion patterns, which can be only partially avoided through planning-time countermeasures. Among possible delivery-time countermeasures, intra-beam motion compensation is capable of improving target coverage. (C) 2014 Elsevier Ireland Ltd. All rights reserved.