BACKGROUND AND PURPOSE Current motion mitigation strategies, like margins, gating, and tracking, deal with geometrical uncertainties in the tumour position, induced by breathing during radiotherapy (RT). However, they often overlook motion variability in amplitude, respiratory rate, or baseline position, when breathing spontaneously. Consequently, this may negatively affect the delivered dose conformality in comparison to the plan. We previously demonstrated on volunteers that 3 different modes of mechanically-assisted and non-invasive ventilation (MANIV) may reduce variability in breathing motion. The volume-controlled mode (VC) constraints the amplitude and respiratory rate (RR) in physiologic condition. The shallow-controlled mode (SH), derived from VC, increases the RR and decreases amplitude. The slow-controlled mode (SL) induces repeated breath holds with constrained ventilation pressure. In this study, we compared these mechanical ventilation modes to spontaneous breathing or breath hold and assessed their tolerance and effects on internal tumour motion in patients receiving RT. MATERIAL AND METHODS The VC and SH modes were evaluated in ten patients with lung or liver cancers (cohort A). The SL mode was evaluated in 12 left breast cancer patients (cohort B). After a training and simulation session, the patients underwent 2 MRI sessions to analyze the internal motion of breast and tumour. RESULTS MANIV was well tolerated, without any adverse events or oxymetric changes, even in patients with respiratory comorbidities. In cohort A, when compared to spontaneous breathing (SP), VC reduced significantly inter-session variations of the tumour motion amplitude (p = 0.01), as well as intra- and inter-session variations of the RR (p < 0.05). As to SH, the RR increased, while its variations within and across sessions decreased when compared to SP (p < 0.001). SH reduced the median amplitude of the tumour motion by 6.1 mm or 38.2% (p ≤ 0.01) compared to VC. In cohort B, breast position stability over the end-inspiratory plateaus obtained spontaneously or with SL remained similar. Median duration of the plateaus in SL was 16.6 s. CONCLUSION MANIV is a safe and well tolerated ventilation technique for patients receiving radiotherapy. MANIV could thus make current motion mitigation strategies less critical and more robust. Clinical implementation might be considered, provided the ventilation mode is carefully selected with respect to the treatment indication and patient individualities.

中文翻译：

---

用于放射治疗的机械辅助和无创通气：一种规范和调节内部肿瘤运动的安全技术

背景和目的当前的运动缓解策略，如边缘、门控和跟踪，处理肿瘤位置的几何不确定性，由放射治疗 (RT) 期间的呼吸引起。然而，当自主呼吸时，他们经常忽视振幅、呼吸频率或基线位置的运动变化。因此，与计划相比，这可能对递送的剂量适形性产生负面影响。我们之前在志愿者身上证明了 3 种不同的机械辅助和无创通气 (MANIV) 模式可以减少呼吸运动的变异性。容量控制模式 (VC) 限制了生理条件下的振幅和呼吸频率 (RR)。源自 VC 的浅层控制模式 (SH) 增加了 RR 并降低了幅度。慢速控制模式 (SL) 会在通气压力受限的情况下诱导重复屏气。在这项研究中，我们将这些机械通气模式与自主呼吸或屏气进行了比较，并评估了它们对接受放疗的患者体内肿瘤运动的耐受性和影响。材料与方法 在 10 名肺癌或肝癌患者（队列 A）中评估了 VC 和 SH 模式。SL 模式在 12 名左侧乳腺癌患者（队列 B）中进行了评估。在训练和模拟课程之后，患者接受了 2 次 MRI 课程，以分析乳房和肿瘤的内部运动。结果 MANIV 耐受性良好，没有任何不良事件或血氧饱和度变化，即使在患有呼吸系统疾病的患者中也是如此。在队列 A 中，与自主呼吸 (SP) 相比，VC 显着减少了肿瘤运动幅度的会话间变化（p = 0.01），以及 RR 的会话内和会话间变化（p < 0.05）。至于 SH，与 SP 相比，RR 增加，而其在会话内和会话间的变化减少（p < 0.001）。与 VC 相比，SH 将肿瘤运动的中值幅度降低了 6.1 毫米或 38.2% (p ≤ 0.01)。在队列 B 中，自发或使用 SL 获得的吸气末平稳期的乳房位置稳定性保持相似。SL 平台的中位持续时间为 16.6 秒。结论 MANIV 是一种安全且耐受性良好的通气技术，适用于接受放射治疗的患者。因此，MANIV 可以使当前的运动缓解策略变得不那么重要且更加稳健。可以考虑临床实施，