ESTRO 2025 - Abstract Book

S1526

Clinical – Mixed sites & palliation

ESTRO 2025

1 Sharett Institute of Oncology, Hadassah Medical Center, Jerusalem, Israel. 2 Division of Biomedical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany. 3 Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany Purpose/Objective: The advent of commercially available vertical computed tomography systems that allow imaging in the upright position has revived interest in gantry-less proton therapy (PT). This approach uses a fixed beamline with patient rotation in the upright position and has the potential to significantly reduce treatment costs while offering anatomical and comfort advantages for selected patients. This study evaluates the feasibility, safety and efficacy of gantry-less image-guided PT [1,2] for the treatment of recurrent head and neck (HN) and brain cancer. Material/Methods: The interim analysis included 20 adults with recurrent HN or brain cancer. All participants had histologically confirmed tumors and an Eastern Cooperative Oncology Group performance status of ≤2. The participants underwent comprehensive pretreatment imaging, upright and supine simulation sessions, and validated quality of life assessments. The treatment planning process involved a comparison of the dosimetric advantages of upright PT versus standard supine photon intensity-modulated radiotherapy (IMRT) in terms of organ-at-risk (OAR) sparing and target coverage. Toxicities were assessed at three-month intervals according to the Common Terminology Criteria for Adverse Events (CTCAE). Patients had a median age of 62 years and 65% were female. Tumor distribution was 80% HN and 20% brain (Table 1). Table 1: Disease and treatment characteristics.