ESTRO 2024 - Abstract Book

S4395

Physics - Intra-fraction motion management and real-time adaptive radiotherapy

ESTRO 2024

accuracy level that has shown to be sufficient to improve treatment quality with 4D optimised techniques [2]. With further image processing techniques, and making use of the additional information in the other two camera views, better tracking accuracy is expected for both carbon and proton radiographs. This work shows the potential for using ion radiography in tracking lung tumours during ion radiotherapy, and how different acquisition parameters affect the quality of images and accuracy of tracking data.

Keywords: tumour motion, ion imaging, ion therapy

References:

1. Brooks ED, Ning MS, Verma V, Zhu XR, Chang JY. Proton therapy for non-small cell lung cancer: the road ahead. Translational Lung Cancer Research. 2019;8(Suppl 2):S202-S212

2. Steinsberger T, Donetti M, Lis M, Volz L, Wolf M, Durante M, Graeff C. Experimental Validation of a Real-Time Adaptive 4D-Optimized Particle Radiotherapy Approach to Treat Irregularly Moving Tumors, International Journal of Radiation Oncology*Biology*Physics, 2023 115(5):1257-1268

3139

Mini-Oral

Validation of MRI-guided MLC tracking of 3D cardiorespiratory motion using time-resolved dosimetry

Prescilla Uijtewaal 1 , Pim T.S. Borman 1 , Peter L. Woodhead 1,2 , Osman Akdag 1 , Bas W. Raaymakers 1 , Martin F. Fast 1

1 University Medical Center Utrecht, Department of Radiotherapy, Utrecht, Netherlands. 2 Elekta, AB, Stockholm, Sweden

Purpose/Objective:

Stereotactic radiotherapy is increasingly used to ablate treatment targets within or in proximity of the heart, including cardiac arrhythmias such as ventricular tachycardia. A major challenge in treating these targets is that they experience complex cardiorespiratory motion, while being situated close to dose-sensitive structures. To minimize radiation induced side-effects, a smaller planning target volume (PTV) and active motion mitigation are desired. We previously demonstrated that MR-guided multi-leaf collimator (MLC) tracking on an MR-linac could effectively compensate idealized 1D cardiorespiratory motion in cranial-caudal (CC) direction [1]. In this study, we implemented MR-guided MLC tracking to mitigate 3D cardiorespiratory motion on an MR-linac, whereby both the MLC leaves and jaws were used to track the 3D motion, using time-resolved dose measurements for validation.

Material/Methods:

All experiments were performed on a 1.5T Unity MR-linac (Elekta AB, Sweden) in research mode.