Beam angle optimization for external beam radiation therapy using sectioning

A method of beam angle optimization for an IMRT radiotherapy treatment, the method comprising:

• providing a patient model including a plurality of planning target volumes (PTVs);
• 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 PTV of the plurality of PTVs:
• for each respective BEV plane of a respective vertex:
• for each respective pixel of the respective BEV plane:
• evaluating a dose of the respective PTV from a respective beamlet originating from the respective vertex and passing through the respective pixel of the respective BEV plane;
• and
• evaluating a respective BEV score of the respective pixel of the respective BEV plane for the respective PTV based at least in part on the dose of the respective PTV from the respective beamlet;
• determining a PTV-specific threshold BEV score for the respective PTV based at least in part on the BEV scores of the pixels of the BEV planes for the respective PTV;
• for each respective BEV plane of the respective vertex:
• determining one or more respective BEV regions of the respective PTV by comparing each respective BEV score of the respective pixel for the respective PTV to the PTV-specific threshold BEV score, wherein pixels within the one or more BEV regions have BEV scores greater than or equal to the PTV-specific threshold BEV score;
• and
• determining a respective BEV region connectivity manifold for the respective PTV representing connections between BEV regions of adjacent vertices;
• and
• selecting a plurality of optimal field geometries for the IMRT radiotherapy treatment based on the BEV region connectivity manifolds for the plurality of PTVs.

A method of beam angle optimization for an IMRT radiotherapy treatment, the method 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:
• for each respective pixel of the respective BEV plane:
• evaluating 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;
• and
• evaluating a respective BEV score of the respective pixel of the respective BEV plane based at least in part on the dose of the first PTV from the respective beamlet;
• determining a global 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 initial BEV regions by comparing the respective BEV score of each respective pixel to the global threshold BEV score, wherein pixels within the one or more initial BEV regions have BEV scores greater than or equal to the global threshold BEV score, and each respective initial BEV region exposes one or more voxels of the first PTV to beamlets corresponding to the respective vertex;
• for each respective voxel of the first PTV:
• determining a voxel-specific threshold BEV score based on the initial BEV regions for the BEV planes, such that the respective voxel is exposed by beamlets corresponding to a pre-determined fraction of a total number of vertices;
• for each respective BEV plane of the respective vertex:
• for each respective pixel of the respective BEV plane:
• determining a local threshold BEV score for the respective pixel based on the voxel-specific threshold BEV score;
• and
• determining one or more BEV regions of the respective BEV plane by comparing the respective BEV score of each respective pixel to the local threshold BEV score, wherein pixels within the one or more BEV regions have BEV scores greater than or equal to the local 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.