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Using Intrafraction Motion Monitoring Data to Make Informed Decisions

N Knutson*, T Mazur, F Reynoso, M Schmidt, G Hugo, S Mutic, Washington University School of Medicine, St. Louis, MO

Presentations

(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: To show the utility of analyzing intra-fraction motion data from frame-less stereotactic radiosurgery treatments in clinical decision-making.
Methods: Real-time intra-fraction motion data (RTD) from optical tracking was collected under an internal review board IRB approved protocol for single fraction and multi fraction stereotactic radiosurgery (SRS) patients. An in-house tool was developed to relay and plot this data to allow for analysis. This collection of data allowed us to answer several questions about our frame-less SRS process. Across our system, two mask systems were being used for SRS. The RTD allowed for the comparison across two different mask types. Mask one being an SRS mask and mask two being standard rigid mask from the same vendor. Data was collected across 939 fractions (394 for mask 1 and 545 for mask 2).
Results: In general, most patients were able to tolerate frame-less SRS using either mask system. It was observed that as the treatment time increased so did intra-fraction motion for both systems. As the treatment time approached 10 minutes, the intra-fraction motion could be as much as 1 mm, which would necessitate intervention due to the 1-2 mm margins used in SRS and therefore even further increase treatment time. It was also observed that the two different mask models did not show significantly different in RTD results across this patient cohort leading us to be able to select the mask with better feedback from patients.
Conclusion: The periodic review of RTD data helped inform several clinical decisions at our institution, such as what mask system we use and how long we allow a patient to be on the table before making re-imaging mandatory. This review also serves a role in the continual quality assurance for our patients and we believe is of great value in data driven decision-making.

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Keywords

Not Applicable / None Entered.

Taxonomy

TH- External Beam- Photons: intracranial stereotactic/SBRT

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