ESTRO 2025 - Abstract Book

Brachytherapy - Gastro-intestinal, paediatric brachytherapy, miscellaneous

S176

ESTRO 2025

186

Digital Poster A dosimetric comparison of different radiotherapy modalities for non-resected liver metastases Cas Stefaan Dejonckheere 1 , Mateusz Bilski 2 , Younèss Nour 1 , Davide Scafa 1 , Paweł Cisek 2 , Katarzyna Korab 3 , Julia Ponikowska 3 , Ewa Rębacz 3 , Sylwia Sroka 3 , Fabian Kugel 1 , Molina Grimmer 1 , Jasmin Holz 1 , Stephan Garbe 1 , Patrick Eich 1 , Eleni Gkika 1 , Gustavo Renato Sarria 1 , Julian Philipp Layer 1 1 Department of Radiation Oncology, University Hospital Bonn, Bonn, Germany. 2 Department of Radiotherapy, Medical University of Lublin, Lublin, Poland. 3 Department of Medical Physics, St. John’s Cancer Center, Lublin, Poland Purpose/Objective: The role of radiotherapy in the context of limited liver metastases is emerging rapidly, with a variety of available technical approaches. Here, we introduce minimally invasive kilovoltage electronic brachytherapy (eBT) with a single needle applicator and provide a dosimetric comparison with other already established radiotherapy modalities for non-resected liver metastases. Material/Methods: This multicentric study included 30 patients previously treated for solitary liver metastases (Fig. 1a). Interstitial high dose-rate brachytherapy (HDR; Fig. 1b), stereotactic body radiation therapy (SBRT; Fig. 1c), and eBT (Fig. 1d) with a single dwelling point were planned with a 25-Gy single fraction and dosimetrically compared. The primary endpoint was difference in healthy liver tissue exposure. Secondary endpoints included target volume coverage, dose to the surrounding organs at risk (OARs), and radiation treatment time. Figure 1

Results: The median (range) lesion volume was 9.3 (2.5−29.7) cm 3 . Mean treatment time was shortest for SBRT (6.1 min vs. 7.8 min for HDR [ p = 0.003] vs. 16.1 min for eBT [ p < 0.001]). Equally, CTV D90% and D95% were superior for SBRT ( p