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Scintillator-Based Motion Monitoring of Electron and Photon External Beam Radiation Therapy

Elizabeth Huynh*, Mandar S. Bhagwat , Dana-Farber Cancer Institute/Brigham and Women's Hospital, Harvard Medical School, Boston, MA


(Sunday, 7/29/2018) 4:00 PM - 4:30 PM

Room: Exhibit Hall | Forum 5

Purpose: Monitoring patient motion during external beam radiation therapy (EBRT) is important to ensure that the optimized dose distribution in the treatment plan is accurately delivered to the patient. Significant motion during treatment that is not accounted for in the treatment plan may result in underdosing the target and overdosing organs at risk. Most existing techniques rely on a surrogate for patient motion, and do not monitor patient motion relative to the radiation field. Here, we developed a new method to monitor motion through visualization of radiation delivery by light emission from a scintillation material placed in the treatment field. We demonstrate its applicability for monitoring motion during electron and photon EBRT that may be used for safety gating or gated treatments.

Methods: Scintillation dots (SDs) composed of a LYSO scintillator powder and polymer were fabricated and placed around the periphery of the treatment field. For electron EBRT, a 6x6cm² field was outlined with SDs in and outside the periphery of the field. For photon EBRT, SDs outlined a 2x2cm² field on a rotating plate, where SDs moved in and out of the treatment field. Electron and photon EBRT experiments were conducted on a Varian TrueBeam linac with 6MeV (1000MU/min) electrons, and 6MV (600MU/min) and 6MV flattening filter free (1400MU/min) photons.

Results: SDs generated blue visible light upon irradiation megavoltage radiation that could be visually monitored through a commercial camera. For electron and photon EBRT, only the SDs that were inside the radiation field illuminated, whereas those outside the field did not. The intensity of emitted light from the SDs was dose rate dependent.

Conclusion: A new technique was developed for monitoring intra-fraction motion by visualizing radiation delivery using SDs during EBRT treatments through commercial cameras. Future work includes automation of signal detection, which is currently being developed.


Not Applicable / None Entered.


TH- RT Interfraction motion management : General (most aspects)

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