Association Between Liver Tumor and Surface Motion From Cine MR Images On An MRI-Linac
Presentations
SU-F-207-5 (Sunday, 7/10/2022) 2:00 PM - 3:00 PM [Eastern Time (GMT-4)]
Room 207
Purpose: Historically, motion correlation between internal tumor and external surrogates have been studied based on limited sets of X-ray or magnetic resonance (MR) images. With the recent clinical implementation of MR-guided linear accelerators, a vast quantity of continuous planar real-time MR imaging data is acquired. In this study, information was extracted from MR cine imaging during liver cancer treatment to establish associations with internal tumor/diaphragm and external surface/skin movement.
Methods: This retrospective study used 305,644 MR image frames acquired over 118 treatment/imaging sessions of the 23 liver cancer patients treated on a MRI-linac. 9 features were automatically determined on each MR image frame: Lung_Area, the posterior (Dia_Post), dome (Dia_Dome), and anterior (Dia_Ant) points of a diaphragmatic curve; the diaphragm curve point (Dia_Max), the chest (Chest) and the belly (Belly) skin points, experiencing the maximum motion ranges; the superior-interior (SI) and posterior-anterior (PA) positions of a target / tracking structure. For every session, correlation analyses were performed twice among the 9 features: 1) over the full set of image frames, and 2) on the set of high amplitude motion frames whose Dia_Dome motions were more than 25% of the full motion range.
Results: 302,812 frames of images were successfully analyzed. For full motion analysis, correlation coefficients were as follows: 0.95±0.07 between SI and any feature among Dia_Post, Dia_Dome, Dia_Max, or Lung_Area; 0.76±0.29 between SI and Belly (with 50% of correlations > 0.87). 114,684 frames of images had high Dia_Dome motions. For this set, correlation coefficients were: 0.92±0.10 between SI and any feature among Dia_Post, Dia_Dome, Dia_Max, or Lung_Area; 0.77±0.27 between SI and Belly (with 50% of correlations > 0.87).
Conclusion: Diaphragmatic motion is highly correlated with liver tumor motion. Belly vertical motion is linearly proportional to liver tumor longitudinal motion in approximately half of the cases.
Keywords
MR, Planar Imaging, Localization
Taxonomy
IM/TH- MRI in Radiation Therapy: MRI/Linear accelerator combined- IGRT and tracking
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