Building Surrogate-Driven Motion Models from Cone-Beam CT via Surrogate-Correlated Optical Flow

Abstract

An iterative approach to building a surrogate-driven motion model exclusively from cone-beam CT projections is presented. At each iteration the motion model is updated via an analytical expression derived from an optical flow-based approach, with corresponding improvements in the motion compensated reconstruction. The differences between the actual and estimated motion, as seen in the projections, are incorporated into a modified CBCT reconstruction. The correlations between these differences and the surrogate signals used in the motion model are also taken into account in determining the motion model updates. The updates are then composed with the previous estimate of the motion model and set as the new estimate of the motion model. New updates to this new estimate can then be calculated.