A global optimization method for three-dimensional conformal radiotherapy treatment planning

Multiple local minima exist in almost every coplanar or non-coplanar radiot herapy treatment planning problem. We used a global optimization method bas ed on topographical information about the distribution of local minima to f ind all local minima and select the best as the global minimum. We uniforml y select N random points from search regions and construct a topographical graph, from which M (M << N) starting points are selected to launch a local search. Because every seed point was at or near the local minimum, the sol utions found by the local search could be used as the final optimization re sults. We verified this algorithm by applying it to three different clinica l cases and comparing the results with those obtained by a local optimizati on method (sequential quadratic programming). The results show that this al gorithm is feasible and efficient.