Intensity modulated radiotherapy inverse planning algorithm
First Claim
1. A method in a computer for optimizing a dosage of intensity modulated radiotherapy (IMRT) comprising:
- dividing a three dimensional (3D) volume into a grid of dose voxels, wherein each dose voxel receives a dose of radiation from at least one pencil beam having a pencil beam weight and a gantry angle;
selecting a first set of dose voxels from said 3D volume positioned within at least one of a planning target volume (PTV), organs at risk (OAR), and normal tissue in a neighborhood of said PTV;
choosing a dose matrix from said first set of dose voxels;
constructing a beam weight vector of individual beam weights for each pencil beam at each gantry angle;
calculating a transfer matrix representing a dose deposition to the dose voxels from each pencil beam with unit beam weight;
inverting said transfer matrix;
performing a matrix multiplication of said inverted transfer matrix and said dose matrix and populating said beam weight vector with the results of said matrix multiplication; and
iteratively modifying a plurality of doses in said dose matrix within a given range, wherein said range has a specific probability distribution function of acceptable dose values, and repeating said matrix multiplication until the negative weights in said beam weight vector are substantially eliminated, resulting in an optimized set of doses.
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Abstract
A method in a computer for optimizing a dosage of intensity modulated radiotherapy (IMRT) comprises the steps of: dividing a three dimensional (3D) volume into a grid of dose voxels, wherein each dose voxel receives a dose of radiation from at least one pencil beam having a pencil beam weight and a gantry angle; selecting a first set of dose voxels from the 3D volume positioned within at least one of a planning target volume (PTV), organs at risk (OAR), and normal tissue in a neighborhood of the PTV; choosing a dose matrix from the first set of dose voxels; constructing a beam weight vector of individual beam weights for each pencil beam at each gantry angle; calculating a transfer matrix representing a dose deposition to the dose voxels from each pencil beam with unit beam weight; inverting the transfer matrix; performing a matrix multiplication of the inverted transfer matrix and the dose matrix and populating the beam weight vector with the results of the matrix multiplication; and iteratively modifying a plurality of doses in the dose matrix within a given range, wherein the range has a specific probability distribution function of acceptable dose values, and repeating the matrix multiplication until the negative weights in the beam weight vector are substantially eliminated, resulting in an optimized set of doses.
84 Citations
43 Claims
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1. A method in a computer for optimizing a dosage of intensity modulated radiotherapy (IMRT) comprising:
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dividing a three dimensional (3D) volume into a grid of dose voxels, wherein each dose voxel receives a dose of radiation from at least one pencil beam having a pencil beam weight and a gantry angle;
selecting a first set of dose voxels from said 3D volume positioned within at least one of a planning target volume (PTV), organs at risk (OAR), and normal tissue in a neighborhood of said PTV;
choosing a dose matrix from said first set of dose voxels;
constructing a beam weight vector of individual beam weights for each pencil beam at each gantry angle;
calculating a transfer matrix representing a dose deposition to the dose voxels from each pencil beam with unit beam weight;
inverting said transfer matrix;
performing a matrix multiplication of said inverted transfer matrix and said dose matrix and populating said beam weight vector with the results of said matrix multiplication; and
iteratively modifying a plurality of doses in said dose matrix within a given range, wherein said range has a specific probability distribution function of acceptable dose values, and repeating said matrix multiplication until the negative weights in said beam weight vector are substantially eliminated, resulting in an optimized set of doses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A computer system that optimizes a dosage of intensity modulated radiotherapy (IMRT) comprising:
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means for dividing a three dimensional (3D) volume into a grid of dose voxels, wherein each dose voxel receives a dose of radiation from at least one pencil beam having a pencil beam weight and a gantry angle;
means for selecting a first set of dose voxels from said 3D volume positioned within at least one of a planning target volume (PTV), organs at risk (OAR), and normal tissue in a neighborhood of said PTV;
means for choosing a dose matrix from said first set of dose voxels;
means for constructing a beam weight vector of individual beam weights for each pencil beam at each gantry angle;
means for calculating a transfer matrix representing a dose deposition to the dose voxels from each pencil beam with unit beam weight;
means for inverting said transfer matrix;
means for performing a matrix multiplication of said inverted transfer matrix and said dose matrix and populating said beam weight vector with the results of said matrix multiplication; and
means for iteratively modifying a plurality of doses in said dose matrix within a given range, wherein said range has a specific probability distribution function of acceptable dose values, and repeating said matrix multiplication until the negative weights in said beam weight vector are substantially eliminated, resulting in an optimized set of doses. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A computer useable information storage medium storing computer readable program code for causing a computer to perform the steps of:
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dividing a three dimensional (3D) volume into a grid of dose voxels, wherein each dose voxel receives a dose of radiation from at least one pencil beam having a pencil beam weight and a gantry angle;
selecting a first set of dose voxels from said 3D volume positioned within at least one of a planning target volume (PTV), organs at risk (OAR), and normal tissue in a neighborhood of said PTV;
choosing a dose matrix from said first set of dose voxels;
constructing a beam weight vector of individual beam weights for each pencil beam at each gantry angle;
calculating a transfer matrix representing a dose deposition to the dose voxels from each pencil beam with unit beam weight;
inverting said transfer matrix;
performing a matrix multiplication of said inverted transfer matrix and said dose matrix and populating said beam weight vector with the results of said matrix multiplication; and
iteratively modifying a plurality of doses in said dose matrix within a given range, wherein said range has a specific probability distribution function of acceptable dose values, and repeating said matrix multiplication until the negative weights in said beam weight vector are substantially eliminated, resulting in an optimized set of doses. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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Specification