Schematic overview of the dose scenario calculations using DIR. In the static dose, the DIR-warped contour from inhale to exhale is used to calculate Dmin based on the exhale dose grid. In the predicted dose, both inhale and exhale grids (imported from TPS) together with the DIR deformation vector field (DVF) are used in a breathing model to cumulate the dose in six weighted steps to include variant contribution of each of the dose grids in the breathing dose. The accumulated dose is the sum of each fraction’s (denoted by FXi in the figure) breathing doses. For each fraction, the inhale CT is first registered to inhale CBCT to account for setup and interfraction motions. Next, the inhale CBCT is registered to exhale CBCT to provide the DVF for the breathing model. The total accumulated dose is the sum of all fractions. The number of fractions is 3 or 4 depending on the patient’s plan. In all three dose experiments, two sets of results are obtained by separate application of morfeus and the Hybrid DIR method.