DOSIMETRIC IMPACT OF INTERPLAY EFFECT ON RAPIDARC LUNG STEREOTACTIC TREATMENT DELIVERY
DOSIMETRIC IMPACT OF INTERPLAY EFFECT ON RAPIDARC LUNG STEREOTACTIC TREATMENT DELIVERY
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DOI：
10.1016/j.ijrobp.2010.02.059
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发表时间：
2011-01-01
影响因子：
7
通讯作者：
Senan, Suresh
中科院分区：
文献类型：
--
作者：
Ong, ChinLoon;Verbakel, Wilko F. A. R.;Senan, Suresh
目的：调容弧治疗（RapidArc; Varian Medical Systems，Palo Alto，CA）允许对I期肺肿瘤进行快速立体定向放射治疗。我们研究了计算和提供的剂量分布之间的差异，以及与呼吸引起的肿瘤motion.Methods和材料的叶相互作用的剂量影响：在20个连续的患者与I期肺癌谁完成RapidArc交付，15个肿瘤运动超过5毫米的四维计算机断层扫描。静态和动态测量用Gafchromic EBT膜（International Specialty Products Inc.，韦恩，新泽西州）在一个类星体运动体模（Modus医疗设备，伦敦，安大略，加拿大）。将静态测量结果与计算的剂量分布进行比较，并将动态测量结果与静态测量结果与正弦运动模式的卷积进行比较。除了临床治疗计划外，还优化了其他病例，以创建过多的多叶准直器调制，并在体模上输送，峰间运动高达25 mm。使用3%剂量差异和2 mm或1 mm距离的伽马分析来评估输送的准确性和相互作用效应的剂量学影响。在静态模式下，体模中双弧输送的胶片剂量测定显示，平均而言，小于3%的测量值的伽马值大于1。临床计划的动态测量显示出与卷积的高度一致性：对于双弧计划，99.5%符合伽马标准。协议的程度是98.5%的计划与过多的多叶准直器调制和25 mm的motion.Conclusions：电影剂量测定表明，RapidArc准确地提供计算的剂量分布和叶和肿瘤运动之间的相互作用是不显着的单馏分治疗时，RapidArc提供了两个不同的弧。(C)2011 Elsevier Inc.
Purpose: Volumetric modulated arc therapy (RapidArc; Varian Medical Systems, Palo Alto, CA) allows fast delivery of stereotactic radiotherapy for Stage I lung tumors. We investigated discrepancies between the calculated and delivered dose distributions, as well as the dosimetric impact of leaf interplay with breathing-induced tumor motion.Methods and Materials: In 20 consecutive patients with Stage I lung cancer who completed RapidArc delivery, 15 had tumor motion exceeding 5 mm on four-dimensional computed tomography scan. Static and dynamic measurements were performed with Gafchromic EBT film (International Specialty Products Inc., Wayne, NJ) in a Quasar motion phantom (Modus Medical Devices, London, Ontario, Canada). Static measurements were compared with calculated dose distributions, and dynamic measurements were compared with the convolution of static measurements with sinusoidal motion patterns. Besides clinical treatment plans, additional cases were optimized to create excessive multileaf collimator modulation and delivered on the phantom with peak-to-peak motions of up to 25 mm. gamma Analysis with a 3% dose difference and 2- or 1-mm distance to agreement was used to evaluate the accuracy of delivery and the dosimetric impact of the interplay effect.Results: In static mode film dosimetry of the two-arc delivery in the phantom showed that, on average, fewer than 3% of measurements had gamma greater than 1. Dynamic measurements of clinical plans showed a high degree of agreement with the convolutions: for double-arc plans, 99.5% met the gamma criterion. The degree of agreement was 98.5% for the plans with excessive multileaf collimator modulations and 25 mm of motion.Conclusions: Film dosimetry shows that RapidArc accurately delivers the calculated dose distribution and that interplay between leaves and tumor motion is not significant for single-fraction treatments when RapidArc is delivered with two different arcs. (C) 2011 Elsevier Inc.