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Abstract
The goal of this project is to conceive an optimization algorithm for high dose rate brachytherapy. The optimization algorithm presented in this thesis (IPSA) describes the clinical conditions by two groups of points in the three-dimensional space: the dwell positions from which the radioactive source may deliver the dose and the dose control points that evaluate the dose delivered to the anatomy from the dwell positions. The dose control point generation routine executed by the algorithm strategically distributes these points in order to insure the control of the clinical objectives. The algorithm can generate and compare several treatment plans based on this model of the clinical conditions. The group of all possible treatment plans forms the solution space. An objective function that mathematically described the clinical objectives and their relative importance associates a quantitative value to each solution. The solution space and objective function carry together a concise description of the optimization problem. The optimization engine conceived to solve this optimization problem must guarantee the quality of the treatment plan selected for each patient. This guarantee is obtained by using optimization engine based on the principle of simulated annealing. The optimization algorithm executes its task in a short time for live treatment planning. The IPSA algorithm has been successfully implanted in three institutions (CHUQ, UCSF and NIH). At the moment, more than 300 patients have been treated at these institutions for a wide variety of anatomical sites. The treatment plans generated are equal (for simple case), even better (for complex cases), than any plans produced by a specialist with the conventional treatment planning tools. The quality of the treatment plans generated is consistent from one patient to another. The algorithm produces treatment plans personalized to each single patient since the whole optimization routine is based on their specific anatomy and implant.