A radiation therapy treatment method includes providing a patient model, dosimetric constraints, delivery motion constraints, and delivery coordinate space of a radiation delivery device, where the delivery coordinate space is represented as a mesh with vertices connected by edges, where the vertices correspond to directions of a beam eye view (BEV) of the radiation delivery device, where each BEV has corresponding area elements resulting from beam collimation. BEV region connectivity manifolds are constructed from the patient model, the dosimetric constraints, the delivery coordinate space, and existing beam trajectories, wherein each of the BEV region connectivity manifolds represents connections between contiguous 2D target regions, where each of the 2D target regions is defined at each of the vertices of the delivery coordinate space. Beam trajectories are selected based on region connectedness information in the BEV region connectivity manifolds, the dosimetric constraints, the delivery motion constraints, and the existing beam trajectories. Radiation is delivered using the radiation delivery device in accordance with the beam trajectories.