BACKGROUND:Organ motion during treatment delivery in radiotherapy (RT) may lead to deterioration of the planned dose, but can be mitigated by dynamic multi-leaf collimator (DMLC) tracking. The purpose of this study was to implement and experimentally validate a method for time-resolved motion including dose reconstruction for volumetric modulated arc therapy (VMAT) treatments delivered with and without DMLC tracking. MATERIAL AND METHODS:Tracking experiments were carried out on a linear accelerator (Trilogy, Varian) with a prototype DMLC tracking system. A motion stage carrying a biplanar dosimeter phantom (Delta4PT, Scandidos) reproduced eight representative clinical tumor trajectories (four lung, four prostate). For each trajectory, two single-arc 6 MV VMAT treatments with low and high modulation were delivered to the moving phantom with and without DMLC tracking. An existing in-house developed program that adds target motion to treatment plans was extended with the ability to split an arc plan into any number of sub-arcs, allowing the calculated dose for different parts of the treatment to be examined individually. For each VMAT sub-arc, reconstructed and measured doses were compared using dose differences and 3%/3 mm γ-tests. RESULTS:For VMAT sub-arcs the reconstructed dose distributions had a mean root-mean-square (rms) dose difference of 2.1% and mean γ failure rate of 2.0% when compared with the measured doses. For final accumulated doses the mean rms dose difference was 1.6% and the γ failure rate was 0.7%. CONCLUSION:The time-resolved motion including dose reconstruction was experimentally validated for complex tracking and non-tracking treatments with patient-measured tumor motion trajectories. The reconstructed dose will be of high value for evaluation of treatment plan robustness facing organ motion and adaptive RT.

译文

背景:放射治疗(RT)进行治疗期间的器官运动可能会导致计划剂量的恶化,但可以通过动态多叶准直仪(DMLC)跟踪来缓解。这项研究的目的是实施并通过实验验证一种用于时间分辨运动的方法,包括采用和不采用DMLC跟踪进行体积调制电弧治疗(VMAT)治疗的剂量重建。
材料与方法:跟踪实验是在具有原型DMLC跟踪系统的线性加速器(Trilogy,Varian)上进行的。携带双平面剂量计体模(Delta4PT,Scandidos)的运动台可再现八种代表性的临床肿瘤轨迹(四肺,四前列腺)。对于每个轨迹,在有和没有DMLC跟踪的情况下,将具有低调制和高调制的两种单弧6 MV VMAT处理传递给运动体模。现有的内部开发程序可以将目标运动添加到治疗计划中,并且可以将电弧计划划分为任意数量的子弧线,从而可以单独检查治疗不同部分的计算出的剂量,从而扩展了功能。对于每个VMAT子电弧,使用剂量差异和3%/ 3 mmγ测试比较重建和测量的剂量。
结果:对于VMAT亚弧,与测量剂量相比,重建的剂量分布的平均均方根(rms)剂量差异为2.1%,平均γ失效率为2.0%。对于最终累积剂量,平均均方根剂量差异为1.6%,γ失效率为0.7%。
结论:包括剂量重建在内的时间分辨运动已通过实验验证,可用于采用患者测量的肿瘤运动轨迹进行复杂的跟踪和非跟踪治疗。重建的剂量对于评估面向器官运动和适应性RT的治疗计划的鲁棒性将具有很高的价值。

+1
+2
100研值 100研值 ¥99课程
检索文献一次
下载文献一次

去下载>

成功解锁2个技能,为你点赞

《SCI写作十大必备语法》
解决你的SCI语法难题!

技能熟练度+1

视频课《玩转文献检索》
让你成为检索达人!

恭喜完成新手挑战

手机微信扫一扫,添加好友领取

免费领《Endnote文献管理工具+教程》

微信扫码, 免费领取

手机登录

获取验证码
登录