The dij struct
The dij struct holds pre calculated dose influence data for inverse planning. The individual fields contain the following information.
Starting from version 3.0.0, the dose grid has been separated from the CT grid, meaning that each can have a separate resolution depending on the application. Therefore, the two substructures doseGrid and ctGrid hold the following information for both the CT and the dose grid.
dij.doseGrid.resolution - dij.ctGrid.resolution
The resolution of an individual voxel in the dose/ct cube in [mm] in x-, y-, and z-direction (Note that the default value for the doseGrid resolution is 2.5 mm, 2.5 mm and 3mm in x-, y- and z- directions, and is not assigned equal to the ct resolution).
dij.doseGrid.dimensions - dij.ctGrid.dimensions
The resulting dose/ct cube dimension in voxels.
dij.doseGrid.numOfVoxels - dij.ctGrid.numOfVoxels
The total number of voxels in the entire dose/ct cube.
dij.numOfBeams
Specifies the number of beams used for dose calculation and consequently inverse planning.
dij.numOfScenarios
Number of scenarios considered during dose calculation. Usually, only one scenario is used. In a special research mode, however, it is possible to compute dose on multiple 4D CT phases, considering isocenter shifts or range uncertainties.
dij.numOfRaysPerBeam
Specifies the number of rays per beam. For photons, this number also corresponds to the number of bixels per beam. For particles however, it is also possible to have multiple spot positions with different energies at the same lateral spot position.
dij.totalNumOfRays
Specifies the total number of all rays, i.e. dij.totalNumOfRays = sum(dij.numOfRaysPerBeam).
dij.totalNumOfBixels
Specifies the total number of bixels over all beams.
dij.bixelNum
Lists the bixel number in an individual beam for all columns in the precomputed influence data. Together with dij.rayNum and dij.beamNum this information facilitates an easy assignment of columns of the influence data to the stf struct.
dij.rayNum
Lists the ray number in an individual beam for all columns in the precomputed influence data. Together with dij.bixelNum and dij.beamNum this information facilitates an easy assignment of columns of the influence data to the stf struct.
dij.beamNum
Lists the beam number for all columns in the precomputed influence data. Together with dij.bixelNum and dij.rayNum this information facilitates an easy assignment of columns of the influence data to the stf struct.
dij.physicalDose
Pre-computed dose influence matrix with dij.doseGrid.numOfVoxels rows and dij.totalNumOfBixels columns stored within a cell array (Note that starting form Version 3.0, this matrix built by default based on numOfVoxels on doseGrid, not the ctGrid). This matrix specifies the dose contribution from every bixel to every voxel, stored with MATLAB's built-in double precision sparse matrix format.
dij.mAlphaDose
Pre-computed alpha*dose matrix with dij.numOfVoxels rows and dij.totalNumOfBixels columns, stored with MATLAB's built-in double precision sparse matrix format within a cell array. This matrix is only computed for biological optimization, where this information is required to compute dose-averaged alpha cubes that are in turn required for three-dimensional RBE modeling.
dij.mSqrtBetaDose
Pre-computed sqrt(beta)*dose matrix with dij.numOfVoxels rows and dij.totalNumOfBixels columns, stored with MATLAB's built-in double precision sparse matrix format within a cell array. This matrix is only computed for biological optimization, where this information is required to compute dose-averaged alpha cubes that are in turn required for three-dimensional RBE modeling.
Screenshot of the dij-struct:
