ABSTRACT
Current methods for intensity-modulated radiotherapy (IMRT) in breast cancer use forward planning based on equivalent radiological path length to design intensity modulated tangential beams. Compared to conventional tangential techniques, dose reduction of organs at risk is limited using these techniques. We developed a method for intensity modulation of multiple beams for adjuvant radiotherapy of breast cancer by application of a virtual bolus defined on CT for inverse optimization. This method enables multibeam IMRT, which provides improved sparing of lung and heart tissue. In this paper, we present the general aspects of this approach and an evaluation of the optimum beam configuration for IMRT based on inverse treatment planning. We compared this method to conventional techniques. Different clinical examples illustrate the possible indications and feasibility of this new approach. This method is superior to conventional techniques because of the reduction of high-dose area of a substantial cardiac volume in those cases where the parasternal lymph nodes are part of the target volume.
