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Monitoring, Mitigation, and Impact of Intrafraction Tumor Motion

J Bertholet1*, B Jones2*, J Lagendijk3*, (1) Inselspital, University Hospital Bern, Bern, BE, CH, (2) University of Colorado School of Medicine, Aurora, CO, (3) University Medical Center Utrecht, Utrecht, NL


(Sunday, 7/12/2020) 10:30 AM - 11:30 AM [Eastern Time (GMT-4)]

Room: Track 5

Intrafraction tumor motion during radiotherapy delivery impacts the delivered dose to both the tumor and surrounding organs at risk. The motion is most often accounted for by safety margins that include the tumor and its anticipated motion with high probability. The motion is typically not monitored during treatment delivery and its impact on the individual treatment consequently remains unknown. This may in particular be of concern for stereotactic treatments, where motion can impact fraction doses considerably and each fraction constitutes a substantial part of the overall treatment course. Intrafraction tumor motion monitoring on a routine basis would allow improved quality assurance, e.g. by confirming if the motion is within its anticipated range or by reconstruction of the delivered tumor dose. If the monitoring is performed in real time it will furthermore allow real-time motion adaptation methods such as gating and tracking. In this session, available methods for real-time motion monitoring will first be reviewed. Next, a concrete example of a motion management program for pancreatic cancer including mitigation methods and assessment of the dosimetric impact will be presented. Finally, the possibilities of improved intrafraction motion management with the MR-linac through its superior soft tissue contrast will be reviewed with a look into future perspectives.

Learning Objectives:
1. To become familiar with currently available methods for real-time tumor motion monitoring during radiotherapy delivery.
2. To learn how a motion management program including mitigation methods and dosimetric impact assessment can be established using pancreatic radiotherapy as an example.
3. To understand the extended possibilities of intrafraction motion management made possible with the MR-linac through an update on the current status and future perspectives.



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