直线加速器立体定向放射外科治疗中表面引导放射治疗检测到的分次内运动的剂量学分析。
Dosimetric Analysis of Intra-Fraction Motion Detected by Surface-Guided Radiation Therapy During Linac Stereotactic Radiosurgery.
作者信息
Foster Ryan D, Moeller Benjamin J, Robinson Myra, Bright Megan, Ruiz Justin L, Hampton Carnell J, Heinzerling John H
机构信息
Levine Cancer Institute, Atrium Health, Concord, North Carolina.
Levine Cancer Institute, Atrium Health and Southeast Radiation Oncology Group, Charlotte, North Carolina.
出版信息
Adv Radiat Oncol. 2022 Dec 27;8(3):101151. doi: 10.1016/j.adro.2022.101151. eCollection 2023 May-Jun.
PURPOSE
Stereotactic radiosurgery (SRS) immobilization with an open face mask is more comfortable and less invasive than frame based, but concerns about intrafraction motion must be addressed. Surface-guided radiation therapy (SGRT) is an attractive option for intrafraction patient monitoring because it is continuous, has submillimeter accuracy, and uses no ionizing radiation. The purpose of this study was to investigate the dosimetric consequences of uncorrected intrafraction patient motion detected during frameless linac-based SRS.
METHODS AND MATERIALS
Fifty-five SRS patients were monitored during treatment using SGRT between January 1, 2017, and September 30, 2020. If SGRT detected motion >1 mm, imaging was repeated and the necessary shifts were made before continuing treatment. For the 25 patients with intrafraction 3-dimensional vector shifts of ≥1 mm, we moved the isocenter in the planning system using the translational shifts from the repeat imaging and recalculated the plans to determine the dosimetric effect of the shifts. Planning target volume (PTV) coverage, minimum gross tumor volume (GTV) dose (relative and absolute), and normal brain V12 were evaluated. Wilcoxon signed rank tests were used to compare planned and simulated dosimetric parameters and median 2 sample tests were used to investigate these differences between cone and multileaf collimator (MLC) plans.
RESULTS
For simulated plans, V12 increased by a median of 0.01 cc ( = .006) and relative GTV minimum dose and PTV coverage decreased by a median of 15.8% ( < .001) and 10.2 % ( < .001), respectively. Absolute minimum GTV dose was found to be significantly lower in the simulated plans ( < .001). PTV coverage decreased more for simulated cone plans than for simulated MLC plans (11.6% vs 4.7%, = .011) but median V12 differences were found to be significantly larger for MLC plans (-0.34 cc vs -0.01 cc, = .011). Differences in GTV minimum dose between cone and MLC plans were not statistically significant.
CONCLUSIONS
SGRT detected clinically meaningful intrafraction motion during frameless SRS, which could lead to large underdoses and increased normal brain dose if uncorrected.
目的
与基于框架的立体定向放射外科（SRS）固定方式相比，使用开放式面罩进行SRS固定更舒适且侵入性更小，但必须解决分次治疗期间运动的问题。表面引导放射治疗（SGRT）是分次治疗期间患者监测的一个有吸引力的选择，因为它是连续的，具有亚毫米级的精度，并且不使用电离辐射。本研究的目的是调查在基于直线加速器的无框架SRS期间检测到的未校正的分次治疗期间患者运动的剂量学后果。
方法和材料
在2017年1月1日至2020年9月30日期间，使用SGRT对55例SRS患者进行治疗期间监测。如果SGRT检测到运动>1毫米，则重复成像，并在继续治疗前进行必要的移位。对于25例分次治疗期间三维矢量移位≥1毫米的患者，我们在计划系统中使用重复成像的平移移位来移动等中心，并重新计算计划以确定移位的剂量学效应。评估计划靶体积（PTV）覆盖率、最小大体肿瘤体积（GTV）剂量（相对和绝对）以及正常脑V12。使用Wilcoxon符号秩检验比较计划和模拟的剂量学参数，并使用中位数双样本检验研究圆锥和多叶准直器（MLC）计划之间的这些差异。
结果
对于模拟计划，V12的中位数增加了0.01 cc（P = 0.006），相对GTV最小剂量和PTV覆盖率分别中位数下降了15.8%（P < 0.001）和10.2%（P < 0.001）。发现模拟计划中的绝对最小GTV剂量显著更低（P < 0.001）。模拟圆锥计划的PTV覆盖率下降比模拟MLC计划更多（11.6%对4.7%，P = 0.011），但发现MLC计划的V12中位数差异显著更大（-0.34 cc对-0.01 cc，P = 0.011）。圆锥和MLC计划之间的GTV最小剂量差异无统计学意义。
结论
SGRT在无框架SRS期间检测到具有临床意义的分次治疗期间运动，如果不校正，这可能导致大量剂量不足和正常脑剂量增加。
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