Optimization of multileaf collimator settings for radiotherapy treatment planning

Multileaf collimators have become available in many radiotherapy treatment centres. The cross section of a beam can be shaped to a projection of the t arget area by moving the leaves of the multileaf collimator into the beam. In this paper, a method is described to optimize the positions of the indiv idual leaves automatically, once the beam directions and weights have been chosen. The individual positions of the leaves are optimized using the vari able metric method. Changes in dose resulting from small leaf movements are computed efficiently using a special method. The optimization method was t ested on a treatment Plan for a phantom patient. It was found that the unne cessary edges of the beams were trimmed efficiently.