Potential role of PET/MRI in radiotherapy treatment planning

State-of-the art radiotherapy (RT) techniques have become extremely flexible. As a consequence, highly conformal target doses in combination with optimal organat-risk sparing are possible. Due to this highly precise application of complex dose distributions, treatments with higher radiation doses in the tumor but without increased toxicity levels are now feasible. This offers the possibility to adapt dose distributions according to individual radiation sensitivities as measured with functional imaging modalities. Recently, combined PET/MRI has become available. This novel hybrid imaging modality offers the possibility to simultaneously image anatomical, functional and molecular characteristics of a tumor. Consequently, PET/MRI may be an optimal basis for RT individualization. This review discusses different potential applications of PET/MRI for RT treatment planning, as well as technical challenges for the integration of multi-parametric PET/MRI data into RT treatment planning.