Multiobjective Inverse Planning for External Beam Radiotherapy: Decoupling the Optimization and Decision Processes

Inverse planning in radiation therapy is a trial and error process and many studies have been published which consider different algorithms, constraints, cases and objective functions. These planning algorithms combine in a specific way the objectives that are in conflict but do not provide the information that is necessary to obtain an optimal solution. Only in the last few years have significant increases in the availability of computing power enabled inverse planning to be performed to provide the information necessary to understand the possibilities of all dose distributions that can be obtained. We consider in this paper this multiobjective approach for external beam radiation therapy inverse planning that decouples the optimization and decision making processes. Inverse planning can now consider the number of beams, their orientation and optimal beam fluences and their dependence on importance factors. In this way it is possible to exploit the possibilities of advanced technologies such as intensity modulated radiation therapy (IMRT) or tomotherapy. Using data mining and visualization techniques a solution can be selected that requires, if possible, a small number of beams, and that also provides the required dose delivery to the target. Additionally, it allows reduction of the dose in the healthy tissue, especially in organs at risk, in such a way that the compromise we have to make for all the objectives in comparison to the best individual values is as small as possible. Multiobjective Inverse Planning for Beam Radiotherapy 2