Bzdusek Karl, Friberger Henrik, Eriksson Kjell, Hårdemark Björn, Robinson David, Kaus Michael
Philips Healthcare, Fitchburg, Wisconsin 53711, USA.
Med Phys. 2009 Jun;36(6):2328-39. doi: 10.1118/1.3132234.
An efficient method for volumetric intensity modulated arc therapy (VMAT) planning was developed, where a single arc (360 degrees or less) is delivered under continuous variation of multileaf collimator (MLC) segments, dose rate, and gantry speed. Plans can be generated for any current linear accelerator that supports these degrees of freedom. MLC segments are derived from fluence maps at relatively coarsely sampled angular positions. The beam segments, dose rate, and gantry speed are then optimized using direct machine parameter optimization based on dose volume objectives and leaf motion constraints to minimize arc delivery time. The method can vary both dose rate and gantry speed or alternatively determine the optimal plan at constant dose rate and gantry speed. The method was used to retrospectively generate variable dose rate VMAT plans to ten patients (head and neck, prostate, brain, lung, and tonsil). In comparison to step-and-shoot intensity modulated radiation therapy, dosimetric plan quality was comparable or improved, estimated delivery times ranged from 70 to 160 s, and monitor units were consistently reduced in nine out of the ten cases by an average of approximately 6%. Optimization and final dose calculation took between 5 and 35 min depending on plan complexity.
开发了一种用于容积调强弧形放疗（VMAT）计划的高效方法，该方法在多叶准直器（MLC）段、剂量率和机架速度持续变化的情况下进行单弧（360度或更小）照射。可以为任何支持这些自由度的现有直线加速器生成计划。MLC段源自相对粗略采样角度位置处的注量图。然后基于剂量体积目标和叶片运动约束，使用直接机器参数优化对射束段、剂量率和机架速度进行优化，以最小化弧形照射时间。该方法可以改变剂量率和机架速度，或者在恒定剂量率和机架速度下确定最优计划。该方法用于对十名患者（头颈部、前列腺、脑、肺和扁桃体）进行回顾性生成可变剂量率VMAT计划。与静态调强放射治疗相比，剂量计划质量相当或有所提高，估计照射时间为70至160秒，并且在十例中有九例的监测单位持续减少，平均减少约6%。根据计划复杂性，优化和最终剂量计算耗时5至35分钟。
