Real-time MRI guidance for x-ray beam radiotherapy has been delivered clinically since 2014. Many engineering challenges of integrating x-ray therapy systems capable of intensity-modulated radiotherapy (IMRT) with MRI scanners have therefore been overcome. As promised with the straightforward concept of using real-time image guidance with superior-quality MRI, early clinical results indicate positive improvements over conventional IGRT, and more challenging tumour sites are being treated. In essence, the x-ray beam-based radiotherapy community is now expanding into the direction of MRI guidance more than ever before. This leads us to propose a new challenge with even higher complexity and higher stakes: what can real-time MRI guidance offer for particle therapy? Particle therapy planning, delivery and outcome are inherently more dependent on having accurate knowledge of the patient anatomy than x-ray therapy. Utilising real-time and anatomically correct patient soft tissue information should expand the horizons in terms of treatment delivery accuracy, however propose a new set of engineering challenges in the already complex domain of particle therapy. In this chapter we provide a broad overview of the important elements of real-time MRI-guided particle therapy (MRPT). This includes the rationale, current literature, treatment workflows, engineering challenges and finally a concept design to illustrate some of the complexities of the modality.
KeywordsMR guidance Proton therapy Charged particles
The author acknowledges funding from NHMRC Programme Grant No. 1036078 and ARC Discovery Grant No. DP120100821. The author also acknowledges a research agreement with Ion Beam Applications (IBA) and helpful discussions with P. J. Keall and P. E. Metcalfe regarding the content of this chapter.
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