Application of multiobjective evolutionary algorithms for dose optimization problems in brachytherapy

Abstract

In High Dose Rate (HDR) brachytherapy the conventional dose optimization algorithms consider the multiple objectives in form of an aggregate function which combines individual objectives into a single utility value. As a result, the optimization problem becomes single ob- jective, prior to optimization. Up to 300 parameters must be optimized satisfying objectives which are often competing. We use multiobjective dose optimization methods where the objectives are expressed in terms of quantities derived from dose-volume histograms or in terms of statistical parameters of dose distributions from a small number of sampling points. For the last approach we compare the optimization results of evolution- ary multiobjective algorithms with deterministic optimization methods. The deterministic algorithms are very e_cient and produce the best re- sults. The performance of the multiobjective evolutionary algorithms is improved if a small part of the population is initialized by deterministic algorithms.