Abdominal, multi-organ, auto-contouring method for online adaptive magnetic resonance guided radiotherapy: An intelligent, multi-level fusion approach.

•MR-ART consists of daily modification of the radiation therapy plan.•Manual contouring is laborious, subject to variability and inconvenient for MR-ART.•An auto-contouring method based on the human processing model is proposed.•The algorithm couples multi-level top-down and bottom-up information.•To our knowledge, this is the first automated contouring approach for T1 MR-ART.