London Regional Cancer Program, London Health Sciences Centre, London, ON, Canada, N6A 5W9.
Department of Medical Biophysics, Western University, London, ON, Canada, N6A 3K7.
Med Phys. 2020 Apr;47(4):1558-1565. doi: 10.1002/mp.14074. Epub 2020 Mar 1.
In a recent article, our group proposed a fast direct aperture optimization (DAO) algorithm for fixed-gantry intensity-modulated radiation therapy (IMRT) called fast inverse direct aperture optimization (FIDAO). When tested on fixed-gantry IMRT plans, we observed up to a 200-fold increase in the optimization speed. Compared to IMRT, rotational volumetric-modulated arc therapy (VMAT) is a much larger optimization problem and has many more delivery constraints. The purpose of this work is to extend and evaluate FIDAO for inverse planning of VMAT plans.
A prototype FIDAO algorithm for VMAT treatment planning was developed in MATLAB using the open-source treatment planning toolkit matRad (v2.2 dev_VMAT build). VMAT treatment plans using one 360 arc were generated on the AAPM TG-119 phantom, as well as sample clinical liver and prostate cases. The plans were created by first performing fluence map optimization on 28° equispaced beams, followed by aperture sequencing and arc sequencing with a gantry angular sampling rate of 4°. After arc sequencing, a copy of the plan underwent DAO using the prototype FIDAO algorithm, while another copy of the plan underwent DAO using matRad's DAO method, which served as the conventional algorithm.
Both algorithms achieved similar plan quality, although the FIDAO plans had considerably fewer hot spots in the unspecified normal tissue. The optimization time (number of iterations) for FIDAO and the conventional DAO algorithm, respectively, were: 65 s (245) vs 602 s (275) in the TG-119 phantom case; 25 s (85) vs 803 s (159) in the liver case; and 99 s (174) vs 754 s (149) in the prostate case.
This study demonstrated promising speed enhancements in using FIDAO for the direct aperture optimization of VMAT plans.
在最近的一篇文章中，我们小组提出了一种用于固定龙门强度调制放射治疗（IMRT）的快速直接孔径优化（DAO）算法，称为快速逆直接孔径优化（FIDAO）。当在固定龙门 IMRT 计划中进行测试时，我们观察到优化速度提高了 200 倍。与 IMRT 相比，旋转容积调制弧形治疗（VMAT）是一个更大的优化问题，并且有更多的传输约束。这项工作的目的是扩展和评估 FIDAO 用于 VMAT 计划的逆规划。
在 MATLAB 中使用开源治疗计划工具包 matRad（v2.2 dev_VMAT build）开发了一个用于 VMAT 治疗计划的原型 FIDAO 算法。在 AAPM TG-119 体模上以及样本临床肝脏和前列腺病例中生成了一个使用 360 度弧形的 VMAT 治疗计划。通过在 28°等间隔射束上进行通量图优化，然后使用 4°的龙门角采样率进行孔径排序和弧形排序来创建计划。弧形排序后，一个计划副本使用原型 FIDAO 算法进行 DAO，而另一个计划副本使用 matRad 的 DAO 方法进行 DAO，后者作为常规算法。
两种算法都实现了类似的计划质量，尽管 FIDAO 计划在未指定的正常组织中具有明显更少的热点。FIDAO 和常规 DAO 算法的优化时间（迭代次数）分别为：在 TG-119 体模病例中为 65s（245）比 602s（275）；在肝脏病例中为 25s（85）比 803s（159）；在前列腺病例中为 99s（174）比 754s（149）。
这项研究表明，在使用 FIDAO 进行 VMAT 计划的直接孔径优化方面，速度有了很大的提高。
