Spirometer-guided breath-hold breast VMAT verified with portal images and surface tracking

Background and purposeFast rotating closed-bore gantry linacs are ideally suited for breath-hold treatments due to reduced imaging delivery times. We evaluated the reproducibility stability of spirometer-guided breast treatments, using intra-bore surface monitoring portal on Halcyon (Varian Medical Systems).Materials methodsSeven left-sided cancer patients were treated in SDX spirometer (Dyn’R) with an integrated boost volumetric arc protocol Halcyon. A dual depth-camera scanning system monitored left breast. The interfraction, intrafraction intrabreath-hold motion was determined anterior-posterior (AP) superior-inferior (SI) direction. Portal images (PI), acquired at a tangential angle manually registered planning-CT determine inter- errors SI tangential-anterior-posterior (“AP”) axis. Correlations between PI deviations investigated. To evaluate workflow efficiency, total time number breath-holds recorded.ResultsSystematic random variability amplitude below 0.7 mm AP 1.2 component as detected by (N = 130). Systematic retrieved from 140) “AP” 2.1 limited correlation found both axes (R2 0.27/0.38, p < 0.01). 75% fractions completed four 82% within 10 min.ConclusionSurface indicated VMAT radiotherapy can be accurately quickly performed linac. Intra-bore proved valuable technique breathing systems.