Carr M A, Gargett M, Stanton C, Zwan B, Byrne H L, Booth J T
Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, New South Wales, Australia.
Institute of Medical Physics, School of Physics, The University of Sydney, Sydney, New South Wales, Australia.
Phys Imaging Radiat Oncol. 2023 Jan 25;25:100419. doi: 10.1016/j.phro.2023.100419. eCollection 2023 Jan.
Deep inspiration breath-hold (DIBH) is a technique that is widely utilised to spare the heart and lungs during breast radiotherapy. In this study, a method was developed to validate directly the intrafraction accuracy of DIBH during breast volumetric modulated arc therapy (VMAT) via internal chest wall (CW) monitoring.
In-house software was developed to automatically extract and compare the treatment position of the CW in cine-mode electronic portal image device (EPID) images with the planned CW position in digitally reconstructed radiographs (DRR) for breast VMAT treatments. Feasibility of this method was established by evaluating the percentage of total dose delivered to the target volume when the CW was sufficiently visible for monitoring. Geometric accuracy of the approach was quantified by applying known displacements to an anthropomorphic thorax phantom. The software was used to evaluate (offline) the geometric treatment accuracy for ten patients treated using real-time position management (RPM)-guided DIBH.
The CW could be monitored within the tangential sub-arcs which delivered a median 89% (range 73% to 97%) of the dose to target volume. The phantom measurements showed a geometric accuracy within 1 mm, with visual inspection showing good agreement between the software-derived and user-determined CW positions. For the RPM-guided DIBH treatments, the CW was found to be within ±5 mm of the planned position in 97% of EPID frames in which the CW was visible.
An intrafraction monitoring method with sub-millimetre accuracy was successfully developed to validate target positioning during breast VMAT DIBH.
深吸气屏气（DIBH）是一种在乳腺癌放疗期间广泛用于保护心脏和肺部的技术。在本研究中，开发了一种方法，通过内部胸壁（CW）监测直接验证乳腺癌容积调强弧形放疗（VMAT）期间DIBH的分次内准确性。
开发了内部软件，用于自动提取并比较电影模式电子射野影像装置（EPID）图像中胸壁的治疗位置与数字重建射线照片（DRR）中乳腺癌VMAT治疗计划的胸壁位置。通过评估当胸壁足够清晰可见以便监测时，给予靶区体积的总剂量百分比，确定了该方法的可行性。通过对拟人化胸部体模施加已知位移，对该方法的几何准确性进行了量化。该软件用于（离线）评估10例使用实时位置管理（RPM）引导的DIBH治疗患者的几何治疗准确性。
在切线子弧内可监测胸壁，这些子弧给予靶区体积的剂量中位数为89%（范围73%至97%）。体模测量显示几何准确性在1毫米以内，目视检查显示软件得出的胸壁位置与用户确定的胸壁位置之间具有良好的一致性。对于RPM引导的DIBH治疗，在胸壁可见的97%的EPID帧中发现胸壁在计划位置的±5毫米范围内。
成功开发了一种具有亚毫米精度的分次内监测方法，以验证乳腺癌VMAT DIBH期间的靶区定位。
