Performance Characterization of a Real-Time Dose Reconstruction Algorithm for Prostate Stereotactic Radiotherapy Treatment
C Sengupta1*, S Skouboe2, D Nguyen1,3,4, T Ravkilde2, P Poulsen2, T Moodie5, P Keall1, (1) ACRF Image X Institute, The University of Sydney, Sydney, NSW, AU, (2) Department of Oncology, Aarhus University Hospital, DK, (3) University of Technology Sydney, Ultimo, NSW, AU, (4) North Sydney Cancer Centre, Royal North Shore Hospital, NSW, AU, (5) Crown Princess Mary Cancer Centre, Sydney, AU
Presentations
PO-GePV-M-83 (Sunday, 7/25/2021) [Eastern Time (GMT-4)]
Purpose: There is a growing awareness that the dose a patient receives in SBRT often differs from the planned dose due to tumor motion. To improve dose accuracy, dose reconstruction should ideally occur during treatment. To address this, a real-time dose reconstruction method, DoseTracker has been developed. In a critical step to its clinical deployment, we benchmark DoseTracker against a treatment planning system (TPS)-based dose reconstruction method for prostate SBRT treatments and hypothesize that the motion-induced dose-errors determined from these two methods should agree.
Methods: Simulated real-time motion-inclusive dose reconstruction was performed using DoseTracker for nine prostate cancer patients who received IGRT with gating during five-fraction SBRT (7.25Gy/Fx) in the TROG-15.01 SPARK trial. Dose reconstruction was performed for both actual-gated (45 fractions) and simulated non-gated sessions (11 fractions). The motion-induced dose-errors were calculated as the difference between planned and motion-inclusive doses using DoseTracker and compared against the motion-induced dose-errors calculated using an iso-center shift method with a clinical TPS. The motion-induced dose-errors were computed for the clinical target volume (CTV), planning target volume (PTV), and, two risk-organs, bladder and rectum.
Results: The median computation time for each dose calculation of DoseTracker ranged from 110-320 ms for calculation volumes ranging from 287-691 cm³. The mean and standard deviation of the differences of the motion-induced dose-errors calculated using DoseTracker and the TPS were 0.02±0.01 Gy for CTV(ΔDmean), 0.02±0.01 Gy for PTV(ΔDmean), 0.04±0.07 Gy for CTV(ΔD100%), 0.03±0.06 Gy for PTV(ΔD95%), 0.02±0.02 Gy for bladder(ΔDmean) and 0.02±0.07 Gy for rectum(ΔDmean). The close agreement in motion-induced dose-errors supports the hypothesis that the performance of DoseTracker is comparable with the TPS-based method for determining motion-induced dose deterioration.
Conclusion: DoseTracker accurately determined motion-induced dose-errors in real-time for a lower pelvic tumor site. This study demonstrates that clinical implementation of real-time motion-inclusive dose reconstruction with DoseTracker is feasible.
Funding Support, Disclosures, and Conflict of Interest: P Keall is supported by an NHMRC Investigator (L3) grant. D T Nguyen is supported by NHMRC and Cancer Institute NSW Early Career Fellowships. Nguyen, O'Brien, Poulsen, and Keall are listed inventors on KIM-related patents. Nguyen and Keall are stock-holders of SeeTreat Pty.
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