ESTRO 2025 - Abstract Book

S4131

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2025

Conclusion: Both immobilization systems provided comparable reproducibility for average translational and rotational displacements. However, the thermoformed mask significantly reduced z-direction displacement. These findings suggest its selective use in patients with higher motion risks or complex targets requiring enhanced immobilization, particularly for tumors in the inferior lobe.

Keywords: Immobilisation, reproductibility, SBRT

3707

Digital Poster Variability of bladder and rectum volumes during adaptive radiotherapy: a preliminary quantitative analysis of intrafractional changes Iwona Dębosz-Suwińska 1 , Dawid Dawid Bodusz 1 , Barbara Bekman 2 , Agnieszka Namysł-Kaletka 1 , Agata Roch Zniszczoł 1 , Jerzy Wydmański 1 1 Radiotherapy Department, Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice, Poland. 2 Treatment Planning Department, Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice, Poland Purpose/Objective: Patients with prostate cancer are obvious candidates for online adaptive radiotherapy (oART). With the implementation of oART, the reproducibility of organ volumes is no longer a prerequisite; however, the entire process