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.