Adjoint transport for dose in beam angle optimization for external beam radiation therapy

Abstract

A method of beam angle optimization for an IMRT radiotherapy treatment includes providing a patient model having one or more regions of interest (ROIs), defining a delivery coordinate space (DCS), for each ROI, solving an adjoint transport to obtain an adjoint solution field from the ROI, for each vertex in the DCS, evaluating an adjoint photon fluence by performing ray tracing of the adjoint solution field, evaluating a dose of the ROI using the adjoint photon fluence, for each vertex in the DCS, evaluating a respective beam's eye view (BEV) score of each pixel of a BEV plane using the doses of the one or more ROIs, determining one or more BEV regions in the BEV plane based on the BEV scores, determining a BEV region connectivity manifold based on the BEV regions, and determining a set of IMRT fields based on the BEV region connectivity manifold.

1 - 9 . (canceled) 
     
     
         10 . A method of beam angle optimization for an IMRT radiotherapy treatment, the method comprising:
 providing a patient model including one or more regions of interest (ROIs) for the IMRT radiotherapy treatment;   defining a delivery coordinate space (DCS) having a set of candidate vertices, each respective candidate vertex defining a respective beam's eye view (BEV) plane;   identifying a plurality of candidate energy modes for the IMRT radiotherapy treatment;   for each respective energy mode of the plurality of candidate energy modes:
 for each respective BEV plane of a respective candidate vertex in the DCS:
 for each respective ROI of the one or more ROIs:
 evaluating a respective dose of the respective ROI from a respective beamlet incident from the respective candidate vertex and passing through a respective pixel of the respective BEV plane using transport solutions for the respective energy mode; 
 evaluating a respective BEV score of the respective pixel using the doses of the one or more ROIs evaluated for the respective beamlet; and 
 determining one or more BEV regions in the respective BEV plane for the respective energy mode based on the BEV scores of the pixels of the BEV planes corresponding to the set of candidate vertices in the DOS; and 
 
 
 determining a respective BEV region connectivity manifold for the respective energy mode based on the BEV regions of the BEV planes of the set of candidate vertices in the DCS, the respective BEV region connectivity manifold representing connections between contiguous BEV regions between adjacent vertices; 
 determining a plurality of candidate sets of IMRT fields by:
 for each respective energy mode of the plurality of candidate energy modes: 
 determining a respective candidate set of IMRT fields based on the respective BEV region connectivity manifold for the respective energy mode, each respective IMRT field defining a beam angle corresponding to a respective vertex in the DOS; and 
 selecting one of the plurality of candidate sets of IMRT fields as an optimal set of IMRT fields based on an objective function, the optimal set of IMRT fields corresponding to an optimal energy mode among the plurality of candidate energy modes. 
 
   
     
     
         11 . The method of  claim 10 , wherein the transport solutions for each energy mode is obtained by using an adjoint transport approach. 
     
     
         12 . The method of  claim 10 , wherein the transport solutions for each energy mode is obtained by using a forward transport approach. 
     
     
         13 . The method of  claim 10 , wherein determining the one or more BEV regions in the respective BEV plane for the respective energy mode comprises:
 determining a respective threshold BEV score for the respective energy mode based on the BEV scores of the pixels of the BEV planes corresponding to the set of candidate vertices in the DOS; and   determining the one or more BEV regions in the respective BEV plane by comparing each respective BEV score of a respective pixel of the respective BEV plane to the respective threshold BEV score for the respective energy mode, wherein pixels within the one or more BEV regions have BEV scores greater than or equal to the respective threshold BEV score.   
     
     
         14 . The method of  claim 10 , wherein the plurality of ROIs includes one or more planning target volumes (PTVs) and one or more organs at risk (OARs), and evaluating the respective BEV score of the respective pixel comprises:
 evaluating a weighted linear combination of the doses of the plurality of ROIs, wherein the dose of a respective ROI that is one of the one or more PTVs has a positive weight, and a dose of a respective ROI that is one of the one or more OARs has a negative weight.   
     
     
         15 . The method of  claim 10 , wherein determining the respective candidate set of IMRT fields comprises performing optimization using a max-distance function using local gradient descent algorithm based on information contained in the respective BEV region connectivity manifold for the respective energy mode. 
     
     
         16 . A method of beam angle optimization in an IMRT radiotherapy treatment, the method comprising:
 providing a patient model including one or more regions of interest (ROIs) for the IMRT radiotherapy treatment;   defining a delivery coordinate space (DCS) having a set of candidate vertices, each respective candidate vertex defining a respective beam's eye view (BEV) plane;   identifying a first energy mode and a second energy mode for the IMRT radiotherapy treatment;   for the first energy mode:
 determining a first BEV region connectivity manifold by evaluating doses of the one or more ROIs for each respective BEV plane corresponding to each respective candidate vertex of the DCS using transport solutions for the first energy mode; 
   for the second energy mode:
 determining a second BEV region connectivity manifold by evaluating doses of the one or more ROIs for each respective BEV plane corresponding to each respective candidate vertex of the DCS using transport solutions for the second energy mode; and 
   determining a set of IMRT fields based on the first BEV region connectivity manifold for the first energy mode and the second BEV region connectivity manifold for the second energy mode, each respective IMRT field of the set of IMRT fields defining a beam angle corresponding to a respective vertex in the DCS.   
     
     
         17 . The method of  claim 16 , wherein the set of IMRT fields includes at least a first IMRT field corresponding to the first energy mode, and at least a second IMRT field corresponding to the second energy mode. 
     
     
         18 . The method of  claim 16 , wherein:
 determining the first BEV region connectivity manifold or the second BEV region connectivity manifold comprises:
 for each respective BEV plane of a respective candidate vertex in the DCS: 
 for each respective ROI of the one or more ROIs:
 evaluating a respective dose of the respective ROI from a respective beamlet incident from the respective candidate vertex and passing through a respective pixel of the respective BEV plane using the transport solutions for the first energy mode or the second energy mode; and 
 evaluating a respective BEV score of the respective pixel using the doses of the one or more ROIs evaluated for the respective beamlet; and 
 
 determining one or more BEV regions in the respective BEV plane for the first energy mode or the second energy mode based on the BEV scores of the pixels of the BEV planes corresponding to the set of candidate vertices in the DOS; and 
 determining the first BEV region connectivity manifold for the first energy mode based on the BEV regions for the first energy mode of the BEV planes of the set of candidate vertices in the DCS, or determining the second BEV region connectivity manifold for the second energy mode based on the BEV regions for the second energy mode of the BEV planes of the set of candidate vertices in the DCS. 
   
     
     
         19 . The method of  claim 16 , wherein the transport solutions for the first energy mode or the second energy mode is obtained by using an adjoint transport approach. 
     
     
         20 . The method of  claim 16 , wherein the transport solutions for the first energy mode or the second energy mode is obtained by using a forward transport approach.