Systems for planning delivery of radiation dose to a target region within a subject comprise a processor configured to: initialize a first plurality of control points located on a trajectory, the trajectory comprising relative movement between a radiation source and the subject, wherein initializing the first plurality of control points comprises assigning, to each the first plurality of control points, one or more axis positions which specify a position of the radiation source relative to the subject； specify a second plurality of control points along the trajectory, the second plurality of control points comprising a larger number of control points than the first plurality of control points； and iteratively optimize a simulated dose distribution over the second plurality of control points to thereby determine a radiation delivery plan by assigning each of the second plurality of control points optimized values for one or more radiation delivery parameters.
