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Session: Multi-Disciplinary General ePoster Viewing [Return to Session]

Clinical Implementation of InBore Real-Time Monitoring for Adaptive Radiotherapy On Ethos

T Keiper*, G Kim, UC San Diego, La Jolla, CA


PO-GePV-M-221 (Sunday, 7/10/2022)   [Eastern Time (GMT-4)]

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Purpose: To commission a workflow for implementation of the first clinical InBore surface-guided radiation therapy (SGRT) system on the Ethos and investigate the monitoring stability for patients during adaptation.

Methods: The InBore system specifications including co-calibration of the camera systems, shift accuracy, and stability were tested on Ethos. A clinical workflow for SGRT during adaptation was developed and implemented. Initial clinical data was collected for 7 fractions on one patient undergoing irradiation of the ovaries. The monitoring surface was defined on the lower abdomen. Monitoring stability was analyzed throughout the adaptation process for the patient. The surface displacement was compared to table shifts from verification CBCT as the ground truth patient motion. Drift for each of the axes was analyzed to determine the most stable axes for monitoring patient motion under respiration.

Results: The InBore system performed as expected using the proposed clinical workflow. Co-calibration of the ceiling and InBore cameras agreed within 0.2 mm/0.2 degrees. Shift accuracy agreed with couch motion within 0.6 mm. Monitoring stability is acceptable for the length of adaptive treatments. The frames-per-second were measured to be around 20 s⁻¹, appropriate for accurate monitoring of the surface and comparable to the ceiling-mounted system. All rotational axes exhibited standard deviation of drift by less than 0.25 degrees on average while only the translational lateral axis variability less than 0.5 mm during adaptation. Verification CBCT confirmed patient motion of <1 mm. The rotational and the lateral axes are promising candidates to monitor patient motion for sites subject to respiration.

Conclusion: The system was successfully commissioned and appropriate for clinical use. The workflow was successfully implemented in the clinic for monitoring during adaptive radiotherapy. Preliminary results must be expanded on for additional treatment sites and site-specific consideration will be given to remove the verification CBCT.

Funding Support, Disclosures, and Conflict of Interest: Grace Kim acknowledges consultant work for Vision RT.


Image Guidance, Patient Movement


TH- External Beam- Photons: Motion management - intrafraction

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