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Abstract

A brachytherapy treatment planning method and apparatus employs an integer linear programming model for the placement of seeds and branch-and-bound and genetic techniques for finding optimized solutions for seed placement problems based on the model. The model uses binary indicator variables to represent the placement or non-placement of seeds in a predetermined three-dimensional grid of potential seed locations. In preferred embodiments, the three dimensional grid of potential locations corresponds to intersections of a rectangular grid of holes from a template used to place the seeds with each of a number of parallel cross-sectional images of the tumor and surrounding tissue. The images themselves are discretized into a number of image points at a granularity which may or may not be equal to the granularity of the template. The dose delivered to each image point is modeled as a linear combination of the indicator variables. A system of linear constraints is imposed to attempt to keep the dose level at each image point within specified bounds. The branch-and-bound and genetic methods may either maximize the sum of rewards associated with achieving the specified bounds or minimize the sum of penalties associated with deviating from the desired bounds.

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First Claim