Garchinger Maier-Leibnitz-Kolloquium: MR-integrated Proton Therapy: motivation, challenges, status and roadmap

by Prof. Aswin L. Hoffmann (Institute of Radiooncology – OncoRay, Helmholtz-Zentrum Dresden-Rossendorf and TU Dresden)

Thursday 6 Jul 2023, 16:15 → 17:15 Europe/Berlin

Lecture Hall, ground floor (west) (LMU building, Am Coulombwall 1, campus Garching)

Image guidance plays a pivotal role in modern radiation therapy to achieve high local control rates and keep side-effects within tolerable levels.  Technological developments in on-board imaging for high-energy X-ray beam therapy (XT) have enabled daily treatment adaptation for anatomical changes that occur in between or during treatment fractions. The rapid adoption of hybrid MR-LINAC systems combining magnetic resonance imaging (MRI) and XT has enabled online adaptive treatment workflows based on high soft-tissue contrast imaging, allowing dose distributions to be tailored and delivered to the individual patient’s changing anatomy with a high targeting precision.  The lack of fast, high soft-tissue contrast image-guidance in particle beam therapy (PT) is considered a major hindrance for exploiting its full potential to outperform image-guided XT for soft-tissue tumors in general, and those that are subject to motion in particular. The successful clinical introduction of the MR-LINAC systems triggered the PT community to consider the feasibility of MRI guidance for PT. Different scenarios for that include near-room, in-room, and in-beam MRI. An overview of potential clinical indications for these scenarios is presented and discussed. Whereas near-room and in-room MRI may account for interfractional changes and enable offline and online adaptive treatments, respectively, but require post-imaging patient repositioning and do not account for intrafractional changes, in-beam MRI would facilitate imaging in treatment position, both prior to and during dose delivery. The latter real-time approach is expected to improve the targeting precision for moving softtissue tumors, which represent a large proportion of clinical cases treated with PT. The added value of MRI-integration in PT is hence expected to be even more favorable than in XT.  However, the full integration of real-time MRI and PT presents a plethora of technical challenges, starting from scanner integration with the beam line, through dosimetry and treatment planning in the presence of the MR magnetic fields, MR-only based treatment planning, online treatment adaptation and quality assurance, up to online MRI-based range verification.  This presentation provides an overview of recent developments and milestones achieved by various groups on the aforementioned topics. A roadmap for the clinical introduction of in-beam MRintegrated PT is presented, showing ongoing research efforts to address the knowledge gaps and remaining challenges to be solved before a first patient can be safely treated with PT inside an inbeam MRI device. These include artifact-free imaging during irradiation, workflow development, and comparative treatment planning studies demonstrating the expected clinical benefit of real-time inbeam MR-integrated PT over CBCT-guided PT, offline MR-guided PT and MR-LINAC treatments for relevant indications in the thorax, abdomen and pelvis.

Hybrid access via ZOOM:
https://lmu-munich.zoom.us/j/98457332925?pwd=TWc3V1JkSHpyOTBPQVlMelhuNnZ1dz09
Meeting ID: 984 5733 2925
Passcode: 979953

 

 

 

kolloquium-06-07-23.pdf