Beam angle optimization for external beam radiation therapy using sectioning

A computer product comprising a non-transitory computer readable medium storing a plurality of instructions that when executed control a computer system to perform beam angle optimization for an IMRT radiotherapy treatment, the instructions comprising:

• providing a patient model including one or more planning target volumes (PTVs), the one or more PTVs including a first PTV;
• defining a delivery coordinate space (DCS) having a plurality of vertices, each respective vertex defining a respective beam's eye view (BEV) plane;
• for each respective BEV plane of a respective vertex, evaluating a respective BEV score of each respective pixel of the respective BEV plane for the first PTV based at least in part on a dose of the first PTV from a respective beamlet originating from the respective vertex and passing through the respective pixel of the respective BEV plane;
• determining a threshold BEV score for the first PTV based on the BEV scores of the pixels of the BEV planes;
• for each respective BEV plane of the respective vertex, determining one or more BEV regions by comparing the respective BEV score of each respective pixel to the threshold BEV score;
• determining a BEV region connectivity manifold for the first PTV representing connections between BEV regions of adjacent vertices;
• and
• selecting a plurality of optimal field geometries for the IMRT radiotherapy treatment based at least in part on the BEV region connectivity manifold for the first PTV.