ESTRO 2025 - Abstract Book

S2839

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2025

2862

Digital Poster Optimizing left-sided breast cancer radiotherapy planning: dosimetric comparative analysis of 3DCRT, VMAT and Hybrid techniques Rocco Mottareale 1,2 , Francesca Buonanno 3 , Valentina d'Alesio 3 , Marcello Serra 3 , Gianluca Ametrano 3 , Cecilia Arrichiello 3 , Sara Falivene 3 , Gaetano Gagliardo 1 , Mariagabriella Pugliese 2 , Maria Quarto 1 , Paolo Muto 3 1 Department of Advanced Biomedical Sciences, Università degli Studi di Napoli Federico II, Napoli, Italy. 2 Department of Physics "Ettore Pancini", Università degli Studi di Napoli Federico II, Napoli, Italy. 3 Department of Radiation Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Napoli, Italy Purpose/Objective: This study aims to assess dosimetric parameters of different radiotherapy planning techniques for left-sided breast cancer patients, comparing conventional Conformal Radiotherapy (3DCRT) and VMAT to hybrid approaches, including: Hybrid Volumetric Arc Therapy (H-VMAT), VMAT "Butterfly" with coplanar narrow arcs (bVMAT), and Hybrid "Butterfly" VMAT (H-bVMAT). Hybrid plans were produced with 70% and 30% dose contribution from 3DCRT and VMAT, respectively. Material/Methods: Ten left breast cancer patients prescribed 40.05Gy in 15 fractions were randomly selected. Treatments were planned using Elekta Monaco TPS, evaluating five techniques: 3DCRT, VMAT, H-VMAT, bVMAT, and H-bVMAT. Dosimetric evaluation included: Conformity Index (CI), Homogeneity Index (HI), low dose spillage and OARs’ sparing were assessed for the left lung, heart, LAD, contralateral breast and lung. Statistical analysis was performed using Kruskal Wallis and Dunn’s post hoc tests. Results: Dosimetric parameters between different planning techniques were compared considering the same target coverage. VMAT and bVMAT showed significant reductions in HI and better dose uniformity compared to 3DCRT (p<0.001,p<0.05 respectively). 3DCRT produced more hot spots than the volumetric and hybrid techniques with a significant reduction in D2% on the PTV (0.001