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Session: Professional General ePoster Viewing [Return to Session]

To Provide a New Method for Early Alert of the Radiation Dose Change Due to Patient’s Physical Change for Adaptive Radiation Therapy (ART)

Yun Wang, Michael Barton, Bernadett Beaman, Steffany Linskey/Indiana University Health


PO-GePV-P-3 (Sunday, 7/10/2022)   [Eastern Time (GMT-4)]

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Purpose: To provide a new method for early alert of the radiation dose change due to patient’s physical change for adaptive radiation therapy (ART).

Methods: The Varian TrueBeam aS1200 portal image device was used during the radiation treatment to record the dose and dose distribution. By directly comparing the daily dose distribution on the portal image with the dose distribution recorded on the first treatment using the same portal image device, it provides an early alert for possible needs of replanning for the ART. To study the validity of this method, a human head&neck phantom was used. A shaped bolus was attached to the head&neck phantom to simulate patient’s physical change. The phantom was treated with the bolus, then the bolus was removed, and the phantom was treated again with the same setup and MU. Two portal images are compared. The magnitude of the dose change and location of the dose changing are analyzed and compare with the TPS calculation. The correlation between the area of physical change and the dose distribution change on the portal image is studied in detail by comparing the exported dose map from TPS to the portal image dose.

Results: The portal image device was able to extend out to record the daily treatment. The recorded dose distributions by the portal image device have reflected the simulated patient physical change. The value of the detected dose change and the location of the dose change on the portal image match the TPS calculations.

Conclusion: The portal image device can be used during radiation treatments to record the dose. The changes of the dose distribution observed on the daily portal images can be used as the early alert for the ART. More quantitative study is needed. Using the method during the actual patient treatment is planned.


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