S2891
RTT - RTT education, training, and advanced practice
ESTRO 2026
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.
Poster Discussion 4517
Deformable registration-based identification of breathing patterns to quantify the clinical Impact of DIBH in right breast cancer radiotherapy Daniele Carlotti 1 , Claudia Tacconi 1 , Cintia De Almeida Ribeiro 1 , Gabriele D'Ercole 1 , Claudio Dionisi 1 , Michele Fiore 1,2 , Carlo Greco 1,2 , Teresa Insero 1 , Edy Ippolito 1,2 , Aurelia Iurato 1 , Corrado Macauda 1 , Valerio Marè 1 , Paola Martucci 1 , Guenda Meffe 1 , Salvatore Minuti 1 , Angelo Montagnoli 1 , Marta Moraschi 1 , Gian Marco Petrianni 1 , Lucrezia Toppi 1 , Lisa Vicenzi 1 , Sara Ramella 1,2 1 Radiation Oncology, Fondazione Policlinico Universitario Campus Bio-Medico, Rome, Italy. 2 Medicine and Surger, Università Campus Bio-Medico di Roma, Rome, Italy Purpose/Objective: This study aims to investigate the use of deformable image registration (DIR) for the determination and characterization of patient-specific breathing patterns, with the objective of quantifying and assessing the clinical benefits of Deep Inspiration Breath Hold (DIBH) in right-sided breast cancer radiotherapy. In order to prepare patients for therapy, it is essential to implement an effective training program designed to teach correct and reproducible breathing techniques. Proper pre-therapy training ensures consistent breath-hold performance, thereby improving the accuracy and reliability of image registration and dose delivery. Material/Methods: A total of 51 patients, with a mean age of 58 years, was included in a monocentric study conducted across two departments. Patient enrollment took place from September 2024 to September 2025. Deformable image registration (DIR) was performed using the ANACONDA algorithm between planning CT scans acquired under free-breathing (FB) and deep inspiration breath hold (DIBH) conditions to map and analyze respiratory-induced anatomical variations. Each DIR result was independently reviewed and validated by an experienced radiation oncologist to 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
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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