ESTRO 2023

Session Item

Intra-fraction motion management and real-time adaptive radiotherapy

Session Code: 7004

Session Type: Poster (Digital)

Track: Physics

Real-time and online adaptive particle therapy in 10 years: a Delphi consensus analysis

Petra Trnkova, Austria

Presentation Number: PO-1880

Abstract

Abstract Title:

Real-time and online adaptive particle therapy in 10 years: a Delphi consensus analysis

Authors:

Petra Trnkova¹, Ye Zhang², Toshiyuki Toshito³, Ben Heijmen⁴, Christian Richter⁵, Marianne Aznar⁶, Francesca Albertini², Alessandra Bolsi², Juliane Daartz⁷, Antje Knopf^2,8, Jenny Bertholet⁹

¹Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria; ²Paul Scherrer Institute, Center for Proton Therapy, Villigen, Switzerland; ³Nagoya City University West Medical Center, Nagoya Proton Therapy Center, Nagoya, Japan; ⁴Erasmus University Medical Center, Department of Radiotherapy, Rotterdam, The Netherlands; ⁵OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden - Rossendorf, Dresden, Germany; ⁶University of Manchester, Division of Cancer Sciences, Faculty of Biology, Medicine and Health, Manchester, United Kingdom; ⁷Massachusetts General Hospital & Harvard Medical School, Department of Radiation Oncology, Boston, USA; ⁸University for Applied Sciences and Arts Northwestern Switzerland, Institute for Medical Engineering and Medical Informatics, School of Life Sciences, Muttenz, Switzerland; ⁹Inselspital, Bern University Hospital, Division of Medical Radiation Physics and Department of Radiation Oncology, Bern, Switzerland

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Purpose or Objective

To collect experts’ opinion on the future of Online Adaptive Particle Therapy (OAPT) and Real Time Motion Management (RRMM) for a vision with a ten-year horizon.

Material and Methods

Following the POP-ART PT survey on current status [1], the present 3-round Delphi consensus study addresses the future of OAPT and RRMM with a panel of 11 experts using questionnaires. Second and third rounds were adapted based on the answers from the previous round to generate controlled opinion feedback (Figure 1). Full consensus (FC) or partial consensus (PC) were reached when all experts agreed or only one expert had a different opinion, respectively.

Results

OAPT will be the method of choice in ten years (PC), mainly in case of variable organ filling and performed with a single in-room imaging modality (FC). There was no consensus on whether offline adaptation will still be performed once OAPT is used clinically. All steps of OAPT require automation to maintain patient throughput (FC). Artificial Intelligence is needed for safe automation, with its central role seen in auto-segmentation (FC). Standardising reporting of endpoints in clinical trials (PC) and cumulative dose reporting (PC) is necessary. It is not currently clear what the best and fastest patient QA method for OAPT will be, and further investigations are required to answer this question (FC). As efficient workflows and tools are medical products, the clinical implementation requires cooperation between industry, research and clinic (FC) with automated and fast systems, reliable deformable registration for dose accumulation, and higher quality in-room imaging identified as the top three priorities (PC). The future importance of MRI-guided PT did not reach consensus.

RRMM is needed for near-real-time OAPT and to treat moving targets (FC) as it mitigates dose deteriorations for both, target and OARs (FC). It should combine multiple approaches, including breath-hold, rescanning, gating, or tracking (FC) based on individual patient selection criteria (FC) and pre-treatment motion characteristics (FC). Optimisation of rescanning parameters, motion model uncertainties and pre-treatment 4D evaluation were considered clinically important (FC). The need to report fractional 4D dose distribution in clinical trials did not reach consensus. 4D dose calculation and its uncertainty evaluation were identified as top requirements (FC). 4D log-file dose reconstruction, (surface) image-based gating/tracking, efficient image guidance and on-board MR guidance were considered of interest but without reaching consensus.

Conclusion

A DELPHI consensus analysis was performed to explore needed developments for OAPT and RRMM. Join efforts between industry, research and clinics are needed to translate innovations into efficient and clinically feasible workflows for broad-scale implementation. Consistent reporting of well-defined endpoints should be included in clinical trials to evaluate the clinical impact of both methods.

[1] Zhang Y, Trnkova P et al, ESTRO 2021