用于聚焦激光加速的甚高能电子束的剂量输送与优化的焦点扫描
Focal-point scanning for dose delivery and optimization with focused laser-accelerated very-high-energy electron beams
AI总结：
针对激光尾场加速器驱动的甚高能电子束，提出焦点扫描方法，通过双偶极聚焦系统优化焦点分布与入射方向，在保证靶区覆盖率的同时显著降低危及器官剂量，接近质子放疗效果。
AI中文摘要：
聚焦的甚高能电子（VHEE）束可在选定深度产生局部剂量增强，但对有限靶区的照射需要协调控制多个焦点位置、入射方向和束权重，同时限制邻近危及器官（OAR）的受照。我们提出了焦点扫描（FPS），一种专为激光尾场加速器（LWFA）驱动的VHEE束开发的剂量输送与优化方法。该方法基于双偶极聚焦系统，可产生单平面束会聚，并通过改变磁场强度调整焦点位置。FPS将焦点分布在计划靶体积内，并根据邻近关键OAR的几何结构确定焦点特异性入射扇区。该方法使用AAPM TG119 C形基准和1例既往治疗的肺癌放疗病例进行评估。在匹配靶区覆盖率时，FPS使TG119核心平均剂量较平行VHEE和调强X射线计划降低约一半，接近单野质子笔形束扫描参考。在肺癌病例中，FPS维持与临床容积调强弧形治疗参考相当的靶区覆盖率，同时降低所有评估OAR的平均剂量；脊髓平均和最大剂量分别降低93.2%和87.2%。在0至10%的均方根能量展宽及150至250 MeV的平顶电子能谱范围内，评估的OAR平均剂量变化很小。这些结果表明，焦点特异性角度选择可将聚焦束物理转化为有效的OAR sparing，并支持FPS作为宽带LWFA-VHEE放疗的计划策略。
英文摘要：
Focused very-high-energy electron (VHEE) beams can produce localized dose enhancement at selected depths, but irradiation of a finite target requires coordinated control of multiple focal positions, incidence directions, and beam weights while limiting exposure of nearby organs at risk (OARs). We present Focal-Point Scanning (FPS), a dose delivery and optimization method developed for laser wakefield accelerator (LWFA)-driven VHEE beams. The method is based on a two-dipole focusing system that produces single-plane beam convergence and allows the focal position to be varied by changing the magnetic field strength. FPS distributes focal points throughout the planning target volume and determines focal-point-specific incidence sectors according to the geometry of nearby critical OARs. The method was evaluated using the AAPM TG119 C-shape benchmark and one previously treated lung radiotherapy case. At matched target coverage, FPS reduced the TG119 Core mean dose by approximately one half relative to parallel VHEE and intensity-modulated x-ray plans, approaching the single-field proton pencil-beam-scanning reference. In the lung case, FPS maintained target coverage comparable to the clinical volumetric modulated arc therapy reference while reducing the mean dose to every evaluated OAR; spinal-cord mean and maximum doses decreased by 93.2% and 87.2%, respectively. The evaluated OAR mean doses varied little across rms energy spreads of 0 to 10% and for a flat-top electron spectrum spanning 150 to 250 MeV. These results demonstrate that focal-point-specific angular selection can translate focused-beam physics into effective OAR sparing and support FPS as a planning strategy for broadband LWFA-VHEE radiotherapy.
