Abstract

Image guided radiation therapy (IGRT) was the key technological development in modern radiation oncology practice within the last decade. The commercial introduction of cone-beam computer tomography (CBCT) images in 2004, led to a step change in nearly all radiation therapy procedures, ranging from the definition of margins on pre-treatment images to on-line reconstruction of delivered doses and automated quality assurance procedures. Central theme of all our efforts in the development of IGRT is to treat the anatomy of the patient observed at time of treatment.

The clinical exploitation of volumetric radiographic imaging at time of the treatment is still a major area of research, especially for anatomical areas that are subject to deformations on a day to day basis. Plan of the day concepts or online re-planning scenarios are under development for many clinical indications and their impact on clinical outcomes is still under evaluation. However, despite the major impact and success of radiographic based IGRT, there are still two major problems to be solved: i) the limited image quality of CBCT images for many treatment sites, especially for tumours in the pelvic area; and ii) the constraints imposed by image acquisition speed and additional imaging dose for the monitoring of intra-fraction organ motion.

Both of these problems are very well addressed with the development of image guided radiation therapy based on magnetic resonance imaging (MRI). MRI guided radiation therapy (MRIgRT) technology offers the next technologically driven step change of our field. The lecture will include: i) selected IGRT projects pursued at ICR/RMH; ii) a report on the status and potential of MRI-guided RT; iii) discuss the plans of MRIgRT at RMH/ICR; iv) a personal view of the further impact of MRIgRT on the way we may deliver radiation therapy in the future.