Department of Radiation Oncology (Maastro), GROW School for Oncology and Reproduction, Maastricht University Medical Center+, Maastricht, The Netherlands.
Department of Radiation Oncology (Maastro), GROW School for Oncology and Reproduction, Maastricht University Medical Center+, Maastricht, The Netherlands.
Int J Radiat Oncol Biol Phys. 2024 Feb 1;118(2):533-542. doi: 10.1016/j.ijrobp.2023.08.059. Epub 2023 Aug 29.
The optimal motion management strategy for patients receiving stereotactic arrhythmia radioablation (STAR) for the treatment of ventricular tachycardia (VT) is not fully known. We developed a framework using a digital phantom to simulate cardiorespiratory motion in combination with different motion management strategies to gain insight into the effect of cardiorespiratory motion on STAR.
The 4-dimensional (4D) extended cardiac-torso (XCAT) phantom was expanded with the 17-segment left ventricular (LV) model, which allowed placement of STAR targets in standardized ventricular regions. Cardiac- and respiratory-binned 4D computed tomography (CT) scans were simulated for free-breathing, reduced free-breathing, respiratory-gating, and breath-hold scenarios. Respiratory motion of the heart was set to population-averaged values of patients with VT: 6, 2, and 1 mm in the superior-inferior, posterior-anterior, and left-right direction, respectively. Cardiac contraction was adjusted by reducing LV ejection fraction to 35%. Target displacement was evaluated for all segments using envelopes encompassing the cardiorespiratory motion. Envelopes incorporating only the diastole plus respiratory motion were created to simulate the scenario where cardiac motion is not fully captured on 4D respiratory CT scans used for radiation therapy planning.
The average volume of the 17 segments was 6 cm (1-9 cm). Cardiac contraction-relaxation resulted in maximum segment (centroid) motion of 4, 6, and 3.5 mm in the superior-inferior, posterior-anterior, and left-right direction, respectively. Cardiac contraction-relaxation resulted in a motion envelope increase of 49% (24%-79%) compared with individual segment volumes, whereas envelopes increased by 126% (79%-167%) if respiratory motion also was considered. Envelopes incorporating only the diastole and respiration motion covered on average 68% to 75% of the motion envelope.
The developed LV-segmental XCAT framework showed that free-wall regions display the most cardiorespiratory displacement. Our framework supports the optimization of STAR by evaluating the effect of (cardio)respiratory motion and motion management strategies for patients with VT.
对于接受立体定向心律失常放射消融术（STAR）治疗室性心动过速（VT）的患者，最佳的运动管理策略尚不完全清楚。我们开发了一个框架，使用数字体模来模拟心肺运动，并结合不同的运动管理策略，以深入了解心肺运动对 STAR 的影响。
4 维（4D）扩展心脏-胸体模（XCAT）通过 17 节段左心室（LV）模型进行扩展，允许在标准化的心室区域放置 STAR 靶标。模拟了自由呼吸、减少自由呼吸、呼吸门控和屏气的心脏和呼吸门控 4D 计算机断层扫描（CT）。心脏运动的呼吸设定为 VT 患者的人群平均值：上下方向分别为 6、2 和 1 毫米，前后方向分别为 2 和 1 毫米，左右方向分别为 1 和 1 毫米。通过将 LV 射血分数降低到 35%来调整心脏收缩。使用包含心肺运动的信封评估所有节段的靶标位移。创建仅包含舒张期加呼吸运动的信封，以模拟用于放射治疗计划的 4D 呼吸 CT 扫描未完全捕获心脏运动的情况。
17 个节段的平均体积为 6 厘米（1-9 厘米）。心脏收缩-舒张导致节段（质心）在上下、前后和左右方向上的最大运动分别为 4、6 和 3.5 毫米。与单个节段体积相比，心脏收缩-舒张导致运动包络增加 49%（24%-79%），而如果同时考虑呼吸运动，则运动包络增加 126%（79%-167%）。仅包含舒张期和呼吸运动的信封平均覆盖运动包络的 68%至 75%。
开发的 LV 节段性 XCAT 框架表明，游离壁区域显示出最大的心肺位移。我们的框架通过评估（心脏）呼吸运动对 VT 患者的影响和运动管理策略，支持 STAR 的优化。
