RESUMEN
Purpose: Radiation therapy for tumors subject to breathing-related motion during breath-holds (BHs) has the potential to substantially reduce the irradiated volume. Mechanically assisted and noninvasive ventilation (MANIV) could ensure the target repositioning accuracy during each BH while facilitating treatment feasibility through oxygen supplementation and a perfectly replicated mechanical support. However, there is currently no clinical evidence substantiating the use of MANIV-induced BH for moving tumors. The aim of this work was, therefore, to evaluate the technique's performance under real treatment conditions. Methods and Materials: Patients eligible for lung or liver stereotactic body radiation therapy were prospectively included in a single-arm trial. The primary endpoint corresponded to the treatment feasibility with MANIV. Secondary outcomes comprised intrafraction geometric uncertainties extracted from real-time imaging, tolerance to BH, and treatment time. Results: Treatment was successfully delivered in 92.9% (13/14) of patients: 1 patient with a liver tumor was excluded because of a mechanically induced gastric insufflation displacing the liver cranially by more than 1 cm. In the left-right/anteroposterior/craniocaudal directions, the recalculated safety margins based on intrafraction positional data were 4.6 mm/5.1 mm/5.6 mm and 4.7 mm/7.3 mm/5.9 mm for lung and liver lesions, respectively. Compared with the free-breathing internal target volume and midposition approaches, the average reduction in the planning target volume with MANIV reached -47.2% ± 15.3%, P < .001, and -29.4% ± 19.2%, P = .007, for intrathoracic tumors and -23.3% ± 12.4%, P < .001, and -9.3% ± 15.3%, P = .073, for upper abdominal tumors, respectively. For 1 liver lesion, large caudal drifts of occasionally more than 1 cm were measured. The total slot time was 53.1 ± 10.6 minutes with a BH comfort level of 80.1% ± 10.6%. Conclusions: MANIV enables high treatment feasibility within a nonselected population. Accurate intrafraction tumor repositioning is achieved for lung tumors. Because of occasional intra-BH caudal drifts, pretreatment assessment of BH stability for liver lesions is, however, recommended.
RESUMEN
BACKGROUND AND PURPOSE: Deep inspiration breath-hold (DIBH) protects critical organs-at-risk (OARs) for adjuvant breast radiotherapy. Guidance systems e.g. surface guided radiation therapy (SGRT) improve the positional breast reproducibility and stability during DIBH. In parallel, OARs sparing with DIBH is enhanced through different techniques e.g. prone position, continuous positive airway pressure (CPAP). By inducing repeated DIBH with the same level of positive pressure, mechanically-assisted and non-invasive ventilation (MANIV) could potentially combine these DIBH optimizations. MATERIALS AND METHODS: We conducted a randomized, open-label, multicenter and single-institution non-inferiority trial. Sixty-six patients eligible for adjuvant left whole-breast radiotherapy in supine position were equally assigned between mechanically-induced DIBH (MANIV-DIBH) and voluntary DIBH guided by SGRT (sDIBH). The co-primary endpoints were positional breast stability and reproducibility with a non-inferiority margin of 1 mm. Secondary endpoints were tolerance assessed daily via validated scales, treatment time, dose to OARs and their inter-fraction positional reproducibility. RESULTS: Differences between both arms for positional breast reproducibility and stability occurred at a sub-millimetric level (p < 0.001 for non-inferiority). The left anterior descending artery near-max dose (14,6 ± 12,0 Gy vs. 7,7 ± 7,1 Gy, p = 0,018) and mean dose (5,0 ± 3,5 Gy vs. 3,0 ± 2,0 Gy, p = 0,009) were improved with MANIV-DIBH. The same applied for the V5Gy of the left ventricle (2,4 ± 4,1 % vs. 0,8 ± 1,6 %, p = 0,001) as well as for the left lung V20Gy (11,4 ± 2,8 % vs. 9,7 ± 2,7 %, p = 0,019) and V30Gy (8,0 ± 2,6 % vs. 6,5 ± 2,3 %, p = 0,0018). Better heart's inter-fraction positional reproducibility was observed with MANIV-DIBH. Tolerance and treatment time were similar. CONCLUSION: Mechanical ventilation provides the same target irradiation accuracy as with SGRT while better protecting and repositioning OARs.