Inverse planning for photon and proton beams.

The concept of inverse planning for intensity-modulated radiation therapy and its application for photon and charged particle beams is presented. Starting from theoretical solutions of the "inverse problem" in radiation therapy, a clinically applied optimization approach is discussed. A central topic is the mathematical formulation of clinical objectives in terms of physical parameters such as dose levels and irradiated volumes. Examples for practical inverse treatment planning and its clinical application for photon beams are provided. Inverse treatment planning of dose delivery techniques with charged particle beams is discussed by extending the conventional planning concept. A new multimodality inverse planning tool is described and applied to an example of comparative planning between photon and proton IMRT.