ESTRO 2025 - Abstract Book

S3302

Physics - Intra-fraction motion management and real-time adaptive radiotherapy

ESTRO 2025

0.04±0.29 mm, -0.01±0.04 mm and 0.04±0.56 mm in the left-right, superior-inferior and anterior-posterior dimensions respectively. The mean and standard deviation of the rotation error were -0.20±0.31º, -0.10±0.24 º and 0.07±0.11º for rotation about the left-right, superior-inferior and anterior-posterior dimensions respectively. The percentage of tracking results within 2 mm of the ground truth was 100.0%, 100.0% and 98.1% in the left-right, superior-inferior and anterior-posterior dimensions respectively. The end-to-end computation time of the system for a single x-ray projection was 13±9 ms. Example motion traces results comparing the measured and ground truth 3D positions are shown in Figure 2.

Conclusion: An in silico characterisation of a real-time prostate cancer 6DoF IGRT system for conventional linear accelerators has demonstrated high geometric fidelity and low computational latency.

Keywords: prostate, gating, motion

References: [1] Tomography–guided stereotactic body radiotherapy for prostate cancer: The MIRAGE randomized clinical trial JAMA Oncol. 2023;9:365-373 [2] Zhang P, Happersett L, Burleson S, et al. Reduction of post-radiotherapy urinary toxicity via intrafractional MV-kV prostate location monitoring International Journal of Radiation Oncology* Biology* Physics. 2024 [3] Keall P, Nguyen DT, O'Brien R, et al. Real-time image-guided ablative prostate cancer radiation therapy: Results from the TROG 15.01 SPARK trial Int J Radiat Oncol Biol Phys. 2020;107:530-538 [4] Nguyen DT, Keall P, Booth J, Shieh C-C, Poulsen P, O’Brien R. A real-time IGRT method using a Kalman filter framework to extract 3D positions from 2D projections Phys Med Biol. 2021;66(21):214001