Are dose calculations during dose optimization in brachytherapy necessary

We consider the problem of anatomy based doseoptimization in brachytherapy. A calculation method for some objective functions and their derivatives is proposed which significantly reduces the number of required operations. The optimization in some cases, ignoring a preprocessing step, is independent of the number of sampling points. The idea is that some of the objectives and their derivatives used for doseoptimization do not require the explicit calculation of dose values. Doseoptimization with the new modified computation method for the objectives and derivatives is, depending on the number of sampling points, up to 100 times faster than the conventional method with dose calculation.