S2950
RTT- RTT operational practice and workflow innovations
ESTRO 2026
ensure clinical reliability. Quantitative metrics derived from the deformation fields were used to assess motion amplitude, lung expansion, and target displacement between breathing modalities. Both FB and DIBH treatment plans were developed, and lung doses were independently evaluated to investigate whether a more appropriate and reproducible breathing pattern could be identified for each patient. Results: The analysis identified two predominant respiratory patterns among the patients: thoracic breathing and diaphragmatic breathing. Diaphragmatic breathing demonstrated higher reproducibility across multiple DIBH acquisitions, indicating more consistent respiratory control. Moreover, at comparable alveolar density within the lung parenchyma, diaphragmatic breathing was associated with a small reduction in high-dose exposure to lung tissue, confirming its potential dosimetric advantage over thoracic breathing. To accurately assess dose distribution, the calculated dose was deformably mapped to account for differences in alveolar density between breathing conditions. A comparative analysis between techniques showed a reduction in lung dose exposure during diaphragmatic respiration. Specifically, the dose–volume parameters D10, D15, D20, D50, D100, and D200 demonstrated lower values for diaphragmatic breathing, indicating improved sparing.
References: [1] Weistrand, O. and Svensson, S. (2015), The ANACONDA algorithm for deformable image registration in radiotherapy. Med. Phys., 42: 40-53.[2] Dose constraints in breast cancer radiotherapy. A critical review De Rose, Fiorenza et al. Radiotherapy and Oncology, Volume 202, 110591[3] Li, Z., Jian, et al. Clinical benefits of deep inspiration breath-hold in postoperative radiotherapy for right-sided breast cancer: a meta-analysis. BMC Cancer 24, 1238 (2024).[4] Mayr, et al. Reducing Cardiac Radiation Dose From Breast Cancer Radiation Therapy With Breath Hold Training and Cognitive Behavioral Therapy. Topics in Magnetic Resonance Imaging 29(3):p 135- 148, June 2020. Keywords: DIR, breathing model, DIBH Digital Poster 4597 Online adaptive radiotherapy using integrated vendor platforms: workflow timings using Radixact® and Raystation. Samira Shire 1 , Sophie Alexander 1 , Aswathi Alexander 1 , Irena Blasiak-Wal 2 , Alex Dunlop 2 , Adriana Guerra 1 , Simrah Jaweria 1 , Susan Lalondrelle 1 , Katy Lonsdale 1 , Chandni Patel 1 , Benjamin Thomas 1 , Shabanaz Boodhoo 1
Conclusion: DIR proved to be an effective tool for quantifying respiratory motion and differentiating individual breathing patterns in right-sided breast radiotherapy. The findings highlight the importance of recognizing and training patients toward a more diaphragmatic breathing strategy to enhance DIBH reproducibility and reduce lung dose. A standardized workflow and a educational video were developed to support patient preparation, aiming to improve treatment quality and safety.
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