Investigating online adaptive workflows for prostate patients on the MR-Linac: an in-silico study (Presentation number OC-0615, oral presentation, Monday, April 23). This study investigated three methods for rapidly adjusting treatment plans to account for changes in rectal volume in patients with prostate cancer. Results show that currently available methods can be used for daily re-planning strategies. The optimal method (Segment Weight and Shape Optimization, or SSO) enabled treatment replanning in 239 seconds, which should be feasible for daily plan adjustment in real-world clinical settings.
Optimizing acquisition speed and contrast of respiratory correlated 4D-MRI on a 1.5T MRI-Linac (Presentation number PV-0535, poster presentation, Monday, April 23). Internal organs can move during radiation therapy due to breathing, digestion and other normal functions. This study assessed the quality of images using several approaches to account for respiratory motion and also sought to identify the optimum speed for acquiring images to account for abdominal motion in healthy volunteers. Motion of internal organs during radiation therapy due to breathing and other anatomic functions. Results show that four-dimensional MR images were successfully acquired on a 1.5T MR-linac with one of the approaches (self-navigated GA-SoS 4D-MRI). They also demonstrate the feasibility of characterizing abdominal motion even when using only 19% - 38% of the captured image data. The ability to accurately characterize motion with a more limited data set should reduce acquisition time, which is an important factor in making MR-linac compatible with real world clinical workflows.
"The 42 abstracts presented at this conference is continued evidence of the intensity of the work of the Elekta MR-linac Consortium which has resulted in 125 scientific papers on Elekta's MR-linac, more than any other MR-guided radiation delivery system," said Elekta CEO, Richard Hausmann. "With this expert community, Elekta has achieved a technical tour-de-force by working with those on the front line of cancer therapy to innovative next-generation technologies that address unmet needs. We recognize the critical role that the consortium members played in making the ability to see what is treated in real-time a reality, and in developing the clinical protocols and processes that will enable MR/RT and transform patient care as we gear up for pending market introduction."

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