ESTRO 2025 - Abstract Book

S2858

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

ESTRO 2025

Conclusion: We found single arc RAD created prostate SBRT plans of equivalent quality to VMAT that required 2 to 3-arcs. Future studies will explore optimal RAD planning parameters and gains in planning efficiency with RAD.

Keywords: RapidArc Dynamic, Prostate SBRT, VMAT

3179

Digital Poster Planning target volume designed by spatial displacement models to spare pharyngeal constrictor muscles in oropharyngeal cancer Mona Arbab 1 , Zihan Yu 2 , Qiaode Ge 2 , Mark Langer 3 1 Radiation oncology, UT Southwestern, Dallas, USA. 2 Mechanical Engineering, Stony Brook University, Stony Brook, USA. 3 Radiation oncology, Indiana University, Indianapolis, USA Purpose/Objective: The isotropic expansion of clinical target volume (CTV) to generate the planning target volume (PTV) does not account for rotations. This can lead to overlap with adjacent structures such as pharyngeal constrictor muscles (PCMs). Dysphagia-optimized radiation therapy used mandatory PCM dose constraints when high dose CTV did not overlap with PCMs and this technique improved patient reported swallowing function [1]. Our work examines whether principal component analysis expressed as Euler angles (PCA) or as dual quaternions may be used to produce a more favorable PTV that ensures tumor coverage but minimizes overlap with PCM. Both methods take rotational and translational displacements in account but do not assume they are independent, for the displacements are linked for off-axis rotations.