Vergleich verschiedener Optimierungskonzepte für die intensitätsmodulierte Strahlentherapie

Abstract

Intensity modulated irradiation beams provide a substantial progress for radiotherapy. Both, the conformity of the dose distribution with the target volume and sparing of organs at risk are improved. The determination of the fluence profiles is an optimization problem. It depends on the formulation of the objective function, whether a meaningful solution can be achieved. The parameters to maximize uncomplicated tumor control directly, are not yet known with sufficient accuracy. In this work, the usual method of minimizing the quadratic deviation between the calculated and desired dose distributions is compared to methods where clinically proven dose constraints are used directly. For the first approach it is necessary to adapt weighting factors interactively in order to achieve the desired result. Algorithms based on the use of dose limits are faster and allow to simulate usual clinical strategies like palliation or curative treatment very easily. The differences of the dose distributions for this strategies are described as a function of the number of beam portals.