ESTRO 2024 - Abstract Book

S3998

Physics - Inter-fraction motion management and offline adaptive radiotherapy

ESTRO 2024

The study evaluated the agreement between reconstructed and measured dose distributions across three different motion configurations: static, 10-, and 20-mm motion amplitudes. The results, quantified by the γ-pass ratio (3 mm/3% criterion and 5% dose threshold), indicate a high level of agreement, as shown in Table 1. Especially, the pass ratios exceeded the clinical threshold (95%), remaining at 95.4%, even in the presence of the largest motion amplitude configuration studied (20 mm). A visual comparison of the dose and γ-pass ratio distributions are shown in Figure 2.

Conclusion:

The 4D dose reconstruction workflow has been successfully validated comparing its computational results with experimental measurements using EBT3 films actively moved by means of a 4D pre-clinical moving phantom. The agreement was obtained for motion amplitudes up to 20 mm using the standard clinical setup, which included robustness setup margins and range uncertainty, dose grid resolution and DIR algorithm. These findings demonstrate the robustness and accuracy of the dose reconstruction method in accounting for motion-induced effects, ensuring that the delivered dose aligns closely with the planned treatment across varying motion scenarios.

Keywords: 4D dose assessment, dose accumulation, IMPT

References:

[1] Meijers A, Knopf AC, Crijns APG, Ubbels JF, Niezink AGH, Langendijk JA, et al. Evaluation of interplay and organ motion effects by means of 4D dose reconstruction and accumulation. Radiotherapy and Oncology 2020;150:268–74. https://doi.org/10.1016/j.radonc.2020.07.055.