MRI is creating a revolution in radiotherapy. Due to innovations in MRI technology like higher field strengths, multi-sense and better gradients, innovative protocols make new contrasts visible and clinically applicable. This multi-parameter imaging of MRI allows tumour characterization and treatment response assessment. The next step is using MRI for guidance of the actual treatment. Unique is the UMC Utrecht development of the MRI linac system, for real-time and on-line guidance of external beam radiotherapy. This MRI linac system has been developed in the UMC Utrecht and is now clinically being introduced in close collaboration with Elekta and Philips. The MR-linac shows the actual soft tissue anatomy during the radiation delivery. The system allows highly precise dose delivery and must be capable to improve local control while minimizing toxicity. The system guides a complete imaging research line on geometrical correct imaging, automatic imaging, real time imaging, automatic segmentation, etc. New clinical procedures are being developed and must be evaluated in clinical studies. MRI guidance is even more important for proton radiotherapy, where the exact depth of the Bragg peak must be controlled real time. We developed the Centre of Image Guided Oncological Interventions (CIGOI). Besides this MRI linac the CIGOI develops MRI guided brachytherapy, MRI guided High Intensity Focused Ultrasound (HIFU) and MRI guided Holmium radio-embolization. Bringing the concept of real time treatment guidance at a new level. Tumour characterization is being developed within the high field MRI group. The presentation during this symposium will give a short introduction to this new treatment concept.