Division of Radiation Oncology, Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan.
Department of Radiation Oncology, National Taiwan University Cancer Center, Taipei, Taiwan.
J Appl Clin Med Phys. 2022 Jul;23(7):e13635. doi: 10.1002/acm2.13635. Epub 2022 May 19.
The Halcyon is a linear accelerator-based treatment machine designed for a high-throughput simplified workflow. The machine features a compact jawless design, dual-layer multileaf collimators, and a single 6-MV flattening filter-free (FFF) beam. However, the machine's 6-MV FFF beam may restrict its applicability to conventional techniques, such as field-in-field (FiF) radiotherapy, for breast cancer treatment. This study developed a practical and efficient hybrid method for imaging, planning, and irradiation procedures for whole-breast irradiation using Halcyon linear accelerators.
The proposed method involves five major steps: (1) field arrangement, (2) planning target volume (PTV) generation and evaluation, (3) basal plan generation, (4) inverse planning intensity-modulated radiation therapy plan generation, and (5) plan evaluation and irradiation. The PTV is generated using isodose curves plotted on the basis of tangential fields, which are applied to create a basal plan. Subsequently, a basal-dose-compensation approach is applied to further optimize the treatment plan. This efficient workflow necessitates executing only one onboard cone-beam computed tomography procedure. This study included 10 patients with early-stage breast cancer who were treated at our center. The performance of the proposed method was evaluated by comparing its corresponding irradiation time and dose statistics with those derived for a dynamically flattened beam-based FiF (DFB-FiF) method.
All plans were normalized to ensure that 98% of the prescribed dose covered 95% of the PTV. On average, the global maximum doses in the proposed and DFB-FiF methods were lower than 106%. The homogeneity index for right-sided (left-sided) breast cancer was 0.053 (0.056) in the proposed method and 0.073 (0.076) in the DFB-FiF method. The dose statistics of normal tissues, including the contralateral breast, heart, and lungs, were comparable between the methods. However, the irradiation time per monitor unit in the proposed method was approximately five times faster than that in the DFB-FiF method, but the planning time and complexity were similar between the methods.
This study developed and evaluated an efficient and practical hybrid method for whole-breast irradiation using the Halcyon. This method can significantly reduce the irradiation time, while providing comparable dose statistics to the DFB-FiF method.
Halcyon 是一种基于直线加速器的治疗设备，设计用于简化高通量工作流程。该设备具有紧凑的无翼设计、双层多叶准直器和单一的 6MV 无均整过滤器（FFF）射束。然而，该设备的 6MVFFF 射束可能会限制其在乳腺癌治疗等常规技术中的适用性，例如场中场（FiF）放射治疗。本研究开发了一种实用且高效的混合方法，用于使用 Halcyon 直线加速器进行全乳房照射的成像、计划和照射程序。
所提出的方法包括五个主要步骤：（1）野设置，（2）计划靶区（PTV）生成和评估，（3）基础计划生成，（4）逆向计划调强放射治疗计划生成，以及（5）计划评估和照射。PTV 是通过在切线野上绘制等剂量曲线生成的，这些曲线用于创建基础计划。随后，应用基础剂量补偿方法进一步优化治疗计划。这种高效的工作流程需要仅执行一次机载锥形束计算机断层扫描程序。本研究包括在我们中心接受治疗的 10 名早期乳腺癌患者。通过比较与动态平坦化束 FiF（DFB-FiF）方法相比，评估所提出方法的照射时间和剂量统计数据来评估该方法的性能。
所有计划均进行归一化处理，以确保 98%的规定剂量覆盖 95%的 PTV。平均而言，所提出方法和 DFB-FiF 方法中的全局最大剂量均低于 106%。右侧（左侧）乳腺癌的均匀性指数分别为 0.053（0.056）和 0.073（0.076）。方法之间的正常组织剂量统计数据，包括对侧乳房、心脏和肺，相似。然而，所提出方法的每个监测单位的照射时间比 DFB-FiF 方法快约五倍，但两种方法的计划时间和复杂性相似。
本研究开发并评估了一种使用 Halcyon 进行全乳房照射的高效实用的混合方法。该方法可以显著减少照射时间，同时提供与 DFB-FiF 方法相当的剂量统计数据。
