ESTRO 2025 - Abstract Book

S1640

Clinical – äediatric tumours

ESTRO 2025

3425

Mini-Oral Dosimetric results and patient reported outcomes in TEDDI: Radiotherapy Delivery in Deep Inspiration for Pediatric Patients, a NOPHO feasibility study Daniella Elisabet Østergaard 1,2 , Anni Young Lundgaard 3 , Hanne Krogh Rose 4 , Jolanta Hansen 5 , Leila Vaalavirta 6 , Miia Mokka 7 , Ivan Richter Vogelius 1,2 , Lisa Lyngsie Hjalgrim 8 , Marianne Aznar 9 , Maja Vestmø Maraldo 1,2 1 Department of Oncology, Rigshospitalet, Copenhagen, Denmark. 2 Faculty of Health and Medical Sciences, Copenhagen University, Copenhagen, Denmark. 3 Department of Oncology, Odense University Hospital, Odense, Denmark. 4 Department of Oncology, Aarhus University Hospital, Aarhus, Denmark. 5 Department of Oncology, RigshAarhus University Hospitalospitalet, Aarhus, Denmark. 6 Department of Radiation Oncology,, Comprehensive Cancer Center, Helsinki University Hospital, Helsinki, Finland. 7 Department of Oncology and Radiotherapy, Turku University Hospital, Turku, Finland. 8 Department of Paediatric Haematology and Oncology, Rigshospitalet, Copenhagen, Denmark. 9 Division of Cancer Sciences, School of Medical Science, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom Purpose/Objective: TEDDI tested the feasibility and reproducibility of deep inspiration breath-hold (DIBH) in paediatric patients referred for radiotherapy (RT). Here, we report the dosimetric benefit of DIBH vs. free-breathing (FB) and patient reported outcomes of TEDDI. Material/Methods: Paediatric patients with the ability to perform three sequential breath-holds of 20 seconds each and, who might be referred for RT of the thorax/upper abdomen, irrespective of cancer type, were recruited. Patients were trained for DIBH at time of staging or planning CT scanning. External gating with an external marker and visual coaching was used. Dosimetric analysis: Planning CT scans were acquired in DIBH and FB leading to two RT plans according to national guidelines for each patient, which was ultimately referred for RT. Patients were treated in DIBH if this resulted in a superior plan, i.e. lower overall dose to the organs at risk than in FB. Patient-reported outcomes (PRO): At one centre, patients were asked to evaluate their experience of DIBH at training (8 questions) and during treatment, with three daily questions and an extended questionnaire at start, midway and end of treatment (8 questions). Answers were either yes/no or on a 5-point Likert scale. Results: A total of 25 patients were enrolled in 3 centres with an even gender distribution (12 girls/13 boys) and a median age of 15 years (9-17y). Twenty-three patients had lymphoma, and two patients had sarcoma (Ewing, synovial). Dosimetric analysis: Eight patients were referred for RT, of those five were treated in DIBH. Figure 1 and 2 demonstrate the mean lung dose, mean heart dose, LungV20, and LungV5, respectively, with the comparative DIBH and FB RT plans. For the five patients treated in DIBH, there was a clear benefit in all four metrics with DIBH. PRO results: Eleven of 25 trained patients rated their experience with DIBH training, which was rated as either “Really good” or “Good” in 10 patients. Of those treated in DIBH (5/8), patients generally felt safe and comfortable doing DIBH throughout the course