ESTRO 2024 - Abstract Book

S4366

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

ESTRO 2024

The E2E methodology developed in this study revealed a systematic discrepancy of 0.7 mm in the longitudinal direction when using the Radixact Synchrony modality, leading to TTE values inadequate for stereotactic treatments. It was not possible to highlight such a systematic error with E2E tests analyzed with a gamma index methodology. The next step after the application of a corrective patch would be to determine a threshold for keeping TTE values below 1mm when correcting target motion using the MLC.

Keywords: End-To-End, Tomohelical, tracking

References:

[1]: Schnarr, E., Beneke, M., Casey, D., Chao, E., Chappelow, J., Cox, A., ... & Maurer, C. (2018). Feasibility of real ‐ time motion management with helical tomotherapy. Medical physics, 45(4), 1329-1337.

[2]: Chen, Q., Rong, Y., Burmeister, J. W., Chao, E. H., Corradini, N. A., Followill, D. S., ... & Smilowitz, J. B. (2023). AAPM Task Group Report 306: Quality control and assurance for tomotherapy: An update to Task Group Report 148. Medical Physics, 50(3), e25-e52.

2604

Poster Discussion

Voxel-based analysis of intra-fraction prostate motion in online adaptive MRgRT

Ivan Coric 1 , David Mönnich 1 , Simon Böke 2 , Cihan Gani 2 , Karim-Maximilian Niyazi 2 , Daniela Thorwarth 1

1 Section for Biomedical Physics, Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany. 2 University Hospital Tübingen, Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany

Purpose/Objective:

The emergence of Magnetic Resonance-guided Radiation Therapy (MRgRT) offers a promising avenue for more precise and personalized radiation treatment. The trend towards hypo-fractionated MRgRT for prostate cancer requires high treatment precision, as inaccuracy can lead to target underdosage and increased toxicity for healthy tissue. A profound assessment of intra-fraction motion (IFM) of the prostate is therefore imperative to determine the impact on target coverage and ultimately define novel margin recipes for online adaptive MRgRT. Currently, the motion of the prostate is determined using rigid registration, introducing uncertainties while prostate deformation, due to the influence of surrounding organs at risk (OAR), is not considered. The aim of this work was to determine the IFM of the prostate during MRgRT using a voxel-based approach and analyze the impact of IFM on the target coverage.

Material/Methods: