Problems of dose modification in total body irradiation.

Physical treatment planning of total body irradiation (TBI) has the goal to optimize the spatial distribution of dose, taking radiobiological requirements and technical possibilities into account. In order to improve the dose homogeneity in the target volume or to reduce dose and dose rate in organs at risk dose modifications are needed to raise or to lower the local dose. Treatment optimization demands to know possible techniques, the methods of individual planning and calculation as well as the limitations of beam modifying aids.