Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique (IREC), Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), Brussels, Belgium; Cliniques Universitaires Saint Luc, Department of Radiation Oncology, Brussels, Belgium.
Université Catholique de Louvain, ImagX-R, Institute of Information and Communication Technologies, Electronics and Applied Mathematics, Louvain-La-Neuve, Belgium.
Radiother Oncol. 2019 Dec;141:283-291. doi: 10.1016/j.radonc.2019.09.021. Epub 2019 Oct 22.
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.
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.
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.
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.
目前的运动缓解策略，如边缘、门控和跟踪，都可以处理放射治疗（RT）期间因呼吸引起的肿瘤位置的几何不确定性。然而，当患者自主呼吸时，它们往往会忽略呼吸幅度、呼吸频率或基础位置的可变性。因此，与计划相比，这可能会对所给予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 种不同模式的机械辅助和非侵入性通气（MANIV）可以减少呼吸运动的可变性。容量控制模式（VC）将幅度和呼吸率（RR）限制在生理状态下。从 VC 衍生而来的浅控模式（SH）增加了 RR 并降低了幅度。慢控模式（SL）通过受约束的通气压力诱导重复的呼吸暂停。在这项研究中，我们将这些机械通气模式与自主呼吸或呼吸暂停进行比较，并评估它们在接受 RT 的患者中的耐受性和对内部肿瘤运动的影响。
在 10 例肺癌或肝癌患者（队列 A）中评估 VC 和 SH 模式。在 12 例左乳腺癌患者（队列 B）中评估 SL 模式。在培训和模拟阶段后，患者接受了 2 次 MRI 检查，以分析乳房和肿瘤的内部运动。
MANIV 耐受性良好，没有任何不良事件或血氧变化，即使是在有呼吸合并症的患者中也是如此。在队列 A 中，与自主呼吸（SP）相比，VC 显著降低了肿瘤运动幅度的组内和组间变化（p=0.01），以及 RR 的组内和组间变化（p<0.05）。至于 SH，与 SP 相比，RR 增加，而其组内和组间变化减少（p<0.001）。与 VC 相比，SH 使肿瘤运动的幅度中位数降低了 6.1mm 或 38.2%（p≤0.01）。在队列 B 中，在吸气末平台上的乳房位置稳定性在自主呼吸或 SL 下获得，结果相似。SL 中的平台中位持续时间为 16.6s。
MANIV 是一种安全且耐受性良好的放疗患者通气技术。因此，MANIV 可以使当前的运动缓解策略不那么关键和更稳健。如果通气模式根据治疗适应证和患者个体特征进行仔细选择，临床实施可能会被考虑。
