S2734
RTT - Patient preparation, immobilisation, and verification protocols
ESTRO 2026
Purpose/Objective: Respiratory gating is a well-established technique for reducing radiation dose to organs of interest, particularly the heart and lungs, in patients treated for breast cancer or ductal carcinoma in situ [1, 2]. Effective implementation of this technique depends on patient cooperation. This study aimed to evaluate whether changes to the patient education process could improve the effectiveness of respiratory gating
in clinical practice. Material/Methods: A revised patient education programme was
introduced in breast cancer radiotherapy to optimise patient preparation for respiratory gating. All patients received standard training during the planning CT scan, with the revised workflow adding written materials and instructional videos beforehand. Two cohorts were compared: patients treated before (March 1–August 31, 2023) and after (March 1–August 31, 2025) the implementation of the revised workflow. Respiratory gating effectiveness was assessed through lung volumes, target coverage, and radiation doses to organs of interest. All patients underwent CT-based planning with respiratory gating, and data were obtained from the planning software. Group differences were analysed using Pearson’s chi-square. Results: Data were available for all patients treated with respiratory gating during the study periods. In total, 471 patients were included in the analysis: 187 treated in 2023 and 284 in 2025. Baseline characteristics were comparable between cohorts: most patients underwent lumpectomy (77% vs 70%), had left-sided tumours (76% vs 71%), and all received 40 Gy in 15 fractions. Lymph node irradiation was delivered in 46% vs 52%, and a simultaneous integrated boost in 20% vs 17%.The mean ipsilateral lung volume increased from 2208 cm ³ (IQR, 1911–2448) in 2023 to 2313 cm ³ (IQR, 2020–2612) in 2025 (p = 0.003), with more patients achieving volumes ≥ 2600 cm ³ and fewer <2000 cm ³ (Table 1, Figure 1). In left-sided tumours (CTVp only), median mean ipsilateral lung dose increased slightly from 4.3 to 4.6 Gy and V5Gy from 17.8% to 18.9%, while V17Gy was unchanged. Heart doses were low overall, but minor increases were observed in left-sided tumours (Table 1). Target coverage remained high (V95_CTVp >99%, V90_CTVn ≥ 96%), with a small improvement in V95_CTVp_breast (p = 0.003). Conclusion: Overall, these findings suggest that enhanced patient education improved respiratory gating performance, resulting in increased lung volumes, and maintained target coverage while keeping organs of interest doses low. Clinically, improved patient gating appears to reduce technical challenges during radiotherapy planning and to enable faster treatment planning (not
Conclusion: The findings showed that BMI does not significantly influence the mean set-up error, but a higher BMI can reduce reproducibility in patient positioning, causing higher variance. These results suggest that, although AC is commonly used for upper abdominal targets, its effectiveness in ensuring consistent positioning may be reduced in patients with higher BMI. Further studies comparing different immobilisation device and assessing lesion motion control are needed to better define the personalized approach for this subgroup. References: - Daly M, McWilliam A, Radhakrishna G, Choudhury A,
Eccles CL. Radiotherapy respiratory motion management in hepatobiliary and pancreatic
malignancies: a systematic review of patient factors influencing effectiveness of motion reduction with abdominal compression. Acta Oncol. 2022;61(7):833- 841. doi:10.1080/0284186X.2022.2073186- Chu KY, Cooke R, Van den Heuvel F, Mukherjee S, Hawkins MA. Impact of abdominal compression on setup error and image matching during radical abdominal radiotherapy. Tech Innov Patient Support Radiat Oncol. 2019;12:28-33. Published 2019 Dec 16. doi:10.1016/j.tipsro.2019.11.003 Keywords: Abdominal compression, SBRT, IGRT Instructional videos optimise patient education in respiratory gating for breast cancer radiotherapy Kristine W Høgsbjerg 1,2 , Janni A Mortensen 3 , Marianne B Johansen 3 , Peter P Schultz 3 , Maiken Schmidt 3 , Emil Rønn 3 , Esben S Yates 3 , Mette S Thomsen 3 , Birgitte V Offersen 1,2 1 Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark. 2 Department of Clinical Medicine, Aarhus University, Aarhus, Denmark. 3 Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark Proffered Paper 3018
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