This work investigates the incorporation of fiducial marker‐based visibility parameters into the optimization of volumetric modulated arc therapy (VMAT) plans. We propose that via this incorporation, one may produce treatment plans that aid real‐time tumor tracking approaches employing exit imaging of the therapeutic beam (e.g., via EPID), in addition to satisfying purely dosimetric requirements. We investigated the feasibility of this approach for a thorax and prostate site using optimization software (MonArc). For a thorax phantom and a lung patient, three fiducial markers were inserted around the tumor and VMAT plans were created with two partial arcs and prescription dose of 48 Gy (4 fractions). For a prostate patient with three markers in the prostate organ, a VMAT plan was created with two partial arcs and prescription dose 72.8 Gy (28 fractions). We modified MonArc to include marker‐based visibility constraints (“hard”and “soft”). A hard constraint (HC) imposes full visibility for all markers, while a soft constraint (SC) penalizes visibility for specific markers in the beams‐eye‐view. Dose distributions from constrained plans (HC and SC) were compared to the reference nonconstrained (NC) plan using metrics including conformity index (CI), homogeneity index (HI), gradient measure (GM), and dose to 95% of planning target volume (PTV) and organs at risk (OARs). The NC plan produced the best target conformity and the least doses to the OARs for the entire dataset, followed by the SC and HC plans. Using SC plans provided acceptable dosimetric tolerances for both the target and OARs. However, OAR doses may be increased or decreased based on the constrained marker location and number of trackable markers. In conclusion, we demonstrate that visibility constraints can be incorporated into the optimization together with dosimetric objectives to produce treatment plans satisfying both objectives. This approach should ensure greater clinical success when applying real‐time tracking algorithms, using VMAT delivery.

中文翻译：

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针对肿瘤追踪的基于标记的VMAT计划优化的可行性研究。

这项工作研究了如何将基于基准标记的可见性参数纳入容积调制电弧治疗（VMAT）计划的优化中。我们建议通过这种合并，除了满足纯粹的剂量学要求外，还可以制定出治疗计划，以利用治疗光束的出口成像（例如，通过EPID）辅助实时肿瘤追踪方法。我们使用优化软件（MonArc）研究了该方法在胸部和前列腺部位的可行性。）。对于胸模和肺部患者，在肿瘤周围插入了三个基准标记，并创建了两个局部弧和48 Gy（4个分数）处方剂量的VMAT计划。对于在前列腺器官中具有三个标记物的前列腺患者，创建了一个VMAT计划，该计划带有两个局部弧和处方剂量72.8 Gy（28个分数）。我们修改了MonArc包括基于标记的可见性约束（“硬”和“软”）。硬约束（HC）对所有标记都具有完全可见性，而软约束（SC）则对光束视线中的特定标记具有可见性。使用包括合格指数（CI），均匀性指数（HI），梯度测量（GM）和剂量达到计划目标体积的95％的指标，将受限计划（HC和SC）的剂量分布与参考非受限（NC）计划进行比较（PTV）和高危器官（OAR）。NC计划为整个数据集提供了最佳的目标一致性和最少的OAR剂量，其次是SC和HC计划。使用SC计划可为目标和OAR提供可接受的剂量学公差。但是，基于受约束的标记位置和可追踪标记的数量，可以增加或减少OAR剂量。总之，我们证明可见性约束可以与剂量学目标一起纳入优化中，以产生满足这两个目标的治疗计划。当使用VMAT交付应用实时跟踪算法时，这种方法应确保更大的临床成功。