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Characterization of the IMRT Performance of a Novel Biology-Guided Radiotherapy (BgRT) Machine Using the TG-119 Methodology

A Purwar*, M Narayanan, S Khan, D Zaks, J White, C Huntzinger, S Shirvani, S Mazin, G Kuduvalli, RefleXion Medical, Hayward, CA


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

Room: AAPM ePoster Library

Purpose: To characterize the IMRT performance of the RefleXion™ X1, a novel biology-guided radiotherapy (BgRT) machine following the TG-119 methodology.

Methods: CT images of the TG-119 phantom setup and the DICOM RT structure sets were input into the X1 TPS and plans were created following DVH goals described in TG-119.

Verification of the TG-119 test plans was done by delivering the plans to solid water. Both point dose differences (DD) as measured with ion chambers and planar gamma measurements as measured with film were performed as recommended. For the film gamma measurements, RIT software was used to define an ROI in the delivered dose region that excludes the low dose region. Gamma Analysis pass (GP) criteria were set to be 3%/3mm with a pass rate of >90%.

Results: The preliminary check using AP/PA fields passed with a DD of 1.2% and a GP of 98.5%. The second preliminary check using a step wedge pattern passed with DDs of 1.55%, 1.85%, 2.20%, 1.00%, and 0.45% and a GP of 98.1%.

The C1 Multi-target passed with DDs of 0.45%, -1.90%, 0.35% and a GP of 90.8%. The C2 Mock Prostate passed with DDs of -0.10%, 0.65% and GPs of 91.7% and 97.1%. The C3 Mock Head/Neck passed with DDs of 0.24% and 1.53% and GPs of 92.18% 90.75%. The C4 C-Shape (Easy) passed with DDs of -0.93% and 1.29% and GPs of 90.5% 93.6%. The C4 C-Shape (Hard) passed with DDs of 0.62% and -1.38% and DPs of 92.0% and 92.2%.

Conclusion: TG-119 tests demonstrated that the X1 TPS was able to create IMRT treatment plans that met the expected goals as outlined in AAPM TG-119 and that these plans were successfully delivered on the X1 machine to within the desired accuracy.

Funding Support, Disclosures, and Conflict of Interest: This research was supported by RefleXion Medical.


Acceptance Testing, Dosimetry, Treatment Planning


TH- External Beam- Photons: Development (new technology and techniques)

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