Spirometer-guided breath-hold breast VMAT verified with portal images and surface tracking. (April 2021)

• Record Type: Journal Article
• Authors: Delombaerde, Laurence; Petillion, Saskia; Weltens, Caroline; Depuydt, Tom
• Is Part Of: Radiotherapy and oncology. Volume 157(2021)
• Page Start: 78
• Page End: 84
• Publication Date: 2021-04
• Subjects: Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2021.01.016
• Languages: English
• ISSNs: 0167-8140

Abstract

Highlights: Spirometer breath-hold VMAT-SIB breast treatments on Halcyon can be performed in 10 min. Intra-bore surface scanning provides continuous monitoring of breath-hold performance. Portal images should be interpreted with caution due to MLC leaf occlusion. Abstract: Background and purpose: Fast rotating closed-bore gantry linacs are ideally suited for breath-hold treatments due to reduced imaging and delivery times. We evaluated the reproducibility and stability of spirometer-guided breath-hold breast treatments, using intra-bore surface monitoring and portal imaging on Halcyon (Varian Medical Systems). Materials and methods: Seven left-sided breast cancer patients were treated in breath-hold using the SDX spirometer (Dyn'R) with an integrated boost volumetric arc protocol on Halcyon. A dual depth-camera surface scanning system monitored the left breast. The interfraction, intrafraction and intrabreath-hold motion was determined in the anterior-posterior (AP) and superior-inferior (SI) direction. Portal images (PI), acquired at a tangential gantry angle were manually registered to the planning-CT to determine inter- and intrafraction breath-hold errors for the SI and tangential-anterior-posterior ("AP") axis. Correlations between PI and surface imaging deviations were investigated. To evaluate workflow efficiency, the total time and the number of breath-holds were recorded. Results: Systematic and random variability of breath-hold amplitude was below 0.7 mm for the AP and below 1.2 mm for the SI component as detected by surface monitoring ( N = 130). Systematic and random errors retrieved from portal images ( N = 140) were below 1.2 mm for the "AP" and 2.1 mm for SI axis. A limited correlation was found between PI and surface monitoring deviations for both the SI and "AP" axes (R 2 = 0.27/0.38, p < 0.01). 75% of fractions were completed using four breath-holds and 82% within 10 min. Conclusion: Surface imaging indicated spirometer-guided breath-hold VMAT breast radiotherapy can be accurately and quickly performed on a closed-bore gantry linac. Intra-bore surface scanning proved a valuable technique for monitoring breathing motion in closed-bore systems.