ESTRO 2024 - Abstract Book

S4109

Physics - Inter-fraction motion management and offline adaptive radiotherapy

ESTRO 2024

always receive their prescribed dose in the simplified ATP workflow , though this may differ in most clinical settings, where weights and shapes are optimised. However, the rectum received an increased dose >5Gy in 40% of cases, suggesting a benefit in using ATS. There does not appear to be a significant correlation between absolute accumulated mean dose and OAR volume change.

Keywords: MR-linac, dose accumulation

References:

[1] Dunlop, A., Mitchell, A., Tree, A., Barnes, H., Bower, L., Chick, J., Goodwin, E., Herbert, T., Lawes, R., McNair, H., McQuaid, D., Mohajer, J., Nilawar, R., Pathmanathan, A., Smith, G., Hanson, I., Nill, S., & Oelfke, U. Daily adaptive radiotherapy for patients with prostate cancer using a high field MR-linac: Initial clinical experiences and assessment of delivered doses compared to a C-arm linac. Clinical and translational radiation oncology, 23, pp. 35–42, 2020. [2] Bertelsen, A. S., Schytte, T., Møller, P. K., Mahmood, F., Riis, H. L., Gottlieb, K. L., Agergaard, S. N., Dysager, L., Hansen, O., Gornitzka, J., Veldhuizen, E., ODwyer, D. B., Christiansen, R. L., Nielsen, M., Jensen, H. R., Brink, C., & Bernchou, U.. First clinical experiences with a high field 1.5 T MR linac. Acta oncologica (Stockholm, Sweden), 58(10), pp. 1352–1357, 2019.

2808

Digital Poster

Off-line plan evaluation with CBCT-Synthesized-CT in patients treated with DIBH for left breast

Anna Delana 1 , Fiorenza De Rose 2 , Lucia Di Brina 2 , Sara Lucidi 2 , Valentina Vanoni 2

1 APSS, Medical Physics, Trento, Italy. 2 APSS, Radiation Oncology, Trento, Italy

Purpose/Objective:

We propose a workflow to evaluate variability in OARs doses and target coverage due to SGRT-IGRT residual error during DIBH radiotherapy.

Material/Methods:

Patients underwent DIBH-RT with the CRAD-Catalyst HD+ system, on Elekta Versa linac, in Volumetric Modulated Arc Therapy (VMAT) technique. Daily CBCTs were acquired and retrospectively analyzed: CBCT were sent to the TPS (Elekta Monaco), co-registered with the DIBH-CT in order to reproduce the patient positioning during the RT session. OARs contours (heart, left anterior descending coronary artery -LAD, ipsilateral lung) and the clinical target volume (CTV) were automatically adapted to the CBCT images and evaluated by two dedicated radiation oncologists and - if