Association of internal and external motion based on cine MR images acquired during real-time treatment on MRI-Linac for lung cancer patients

PurposesWith the recent clinical implementation of MR-guided linear accelerators, a large amount real-time planar MR images have been acquired during lung cancer treatment as standard care. In this study, associations among tumor, diaphragm, and external skin movement were studied based on cine imaging entire duration each fraction.Methods MaterialsThis retrospective study used 181,798 image frames over 55 treatment/imaging sessions 13 patients treated two MRI-guided accelerators. From frame, in-house software automatically extracted nine features: superior-interior (SI) posterior-anterior (PA) positions tumor; area (Lung_Area); posterior (Dia_Post), dome/apex (Dia_Dome), anterior (Dia_Ant) points diaphragmatic curve; diaphragm curve point (Dia_Max), chest (Chest) belly (Belly) points. Correlation analyses performed 9 features for every session. Lung tumor motion range deviations calculated obtained in Cine compared with ranges from 4D CT images.Results177,009 successfully analyzed. For all patients, correlation coefficients follows: 0.91 ± 0.10 between any Lung_Area, Dia_Post, Dia_Dome, Dia_Max; 0.82 0.21 SI feature 0.75 0.24 Belly. Six considered amplitude (patients deviation greater than 5 mm). 92,956 analyzed 6 large-amplitude patients. set, 0.93 0.07 0.94 0.06 0.90 0.09 Belly.ConclusionBoth motions assessed by are highly correlated longitudinal axis.