Brachytherapy Treatment Planning Method And Apparatus
Techniques for planning the placement of seeds for a brachytherapy treatment of diseased tissue include representing a placement or non-placement of a seed in each point of a predetermined three dimensional grid of potential seed locations with a binary indicator variable. A tumor and surrounding tissue are represented as a predetermined three dimensional tissue grid having a plurality of tissue points. At least one of an upper bound and a lower bound for a dose of radiation received is associated with each point in the tissue grid. An objective value is calculated based on a difference at each point of the tissue grid between an amount of radiation based on a trial placement of seeds and the upper bound or the lower bound of both. The trial placement of seeds is varied and the objective value is again calculated, thereby resulting in additional objective values. An optimal objective value is selected from the calculated objective value and the additional objective values. The planned placement of seeds is set based on the trial placement of seeds that obtains the optimal objective value. Preferably, the tumor and surrounding tissue are represented based on biological imaging. A larger upper bound is preferably associated with fast-proliferating tumor cells than with slowly-proliferating tumor cells. Additionally, the tissue grid may represent the tumor and surrounding tissue at a particular time. In some of these cases, the three dimensional grid of potential seed locations at a time of seed insertion is mapped to a new grid of potential seed locations at the particular time.
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