Beam angle optimization in particle therapy with OptiC

Abstract

Within the last years particle therapy with protons and carbon ions has gained more attention due to the possibility of creating highly conformal dose distributions combined simultaneously with efficient sparing of organs at risk. Although most of the treatments are conducted with static beam lines, some newer facilities are able to provide dose delivery with flexible gantries. The quality of the treatment plan is affected exceedingly by the selected set of beam angles. Because the optimal set of beams is often non-intuitive, a new algorithm for beam angle optimization has been developed. Due to the different dose distribution of particles compared to photons the algorithm was adapted to the special conditions of particle therapy. The algorithm is implemented in our in-house developed treatment planning system OptiC. In order to avoid long computation times, special assumptions are made to speed up dose calculation and the optimization loop. This paper will show the basic mode of action and compare the fast acquired, predicted dose with regularly calculated dose distributions. Finally, the beam angle optimization algorithm was revised on a clinical prostate cancer treatment plan. © 2009 Springer-Verlag.