ESTRO 2024 - Abstract Book

S4391

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

ESTRO 2024

Evaluating plan complexity is an important part of plan QA processes especially when only calculation-based QA is possible due to online adapted treatment plans. In this case, the patient is on-couch when the new plan is generated. We found retrospectively, that the complexity scores showed strong correlation between each other, therefore a single selected one or the average of distal and proximal scores is appropriate to use for evaluation. Plan complexity between original scheduled and online created adapted plans can vary a lot, and therefore it is worth further investigating whether it can deteriorate plan quality in other respects.

Keywords: adaptive radiotherapy, complexity score, Ethos

References:

[1] Tamura, M., Matsumoto, K., Otsuka, M., & Monzen, H. (2020). Plan complexity quantification of dual-layer multi leaf collimator for volumetric modulated arc therapy with Halcyon linac. Physical and Engineering Sciences in Medicine, 43, 947-957. doi:10.1007/s13246-020-00891-2

3045

Digital Poster

First results of real-time motion imaging using integrated-mode ion radiography for tumour motion

Ryan Fullarton 1 , Mikaël Simard 1 , Lennart Volz 2 , Daniel Robertson 3 , Gary Royle 1 , Christoph Schuy 2 , Sam Beddar 4 , Christian Graeff 2 , Charles-Antoine Collins-Fekete 1 1 University College London, Department of Medical Physics and Biomedical Engineering, London, United Kingdom. 2 GSI Helmholtz Centre for Heavy Ion Research GmbH, Biophysics, Darmstadt, Germany. 3 Mayo Clinic Arizona, Division of Medical Physics, Phoenix, USA. 4 The University of Texas MD Anderson Cancer Center, Department of Radiation Physics, Houston, USA

Purpose/Objective:

The motion of lung tumours presents a challenge for the accurate delivery of conformal ion therapy. Tracking the motion of lung tumours during the delivery provides a means of mitigating this problem through gating tumour tracking, or plan adaptation [1]. Integrated mode ion radiographs, with fast acquisition speeds, provide the opportunity to image moving targets in ion radiotherapy and provide the motion data on which to base tumour tracking. This work shows the first experimentally acquired proton and carbon ion radiographs of moving objects using an integrated-mode ion radiography system.

Material/Methods:

The detector consists of a monolithic block of plastic scintillator (20 cm x 20 cm x 25 cm) viewed from three angles (lateral, top and distal) by digital cameras to capture the light produced by the ion beams. Proton and carbon