ESTRO 2025 Congress Report I Debate I Interdisciplinary Track

Report by the ESTRO positioning & immobilisation focus group

 

The second debate at ESTRO 2025 engaged the audience with a highly provocative motion: “This house believes that [cone-beam CT] CBCT-based fast adaptation workflows will supersede broad MR-Linac usage.” This topic resonates deeply with the clinical, strategic and economic realities of many radiotherapy departments.

 

Even before the debate began, the audience seemed to have made up its mind: an initial live poll showed 72% in favour of the motion and only 28% against. With this backdrop, the speakers against the motion faced a significant challenge.

The debate was opened by Nika Guberina (Germany), who spoke in favour of the motion. She demonstrated how CBCT-based online adaptive radiotherapy (oART), enhanced through the use of artificial intelligence and streamlined workflows, enabled clinically effective, safe and efficient adaptability. The workflow—based on CBCT for positioning, automatic segmentation, and plan comparison—was shown to save time and dose while maintaining high standards. Clinical cases highlighted its versatility across various anatomical sites, even without MR. Due to recent improvements in image quality, CBCT-based oART is now considered suitable for the majority of treatments.

Simeon Nill (UK) countered strongly with a shift of the discussion to a conceptual level. “Would we ever ask whether CT will supersede MR in radiology?” he asked provocatively. For him, MR-Linac had brought a turning point in radiotherapy: it offered superior soft-tissue contrast, real-time monitoring, and a unique potential for biologically guided adaptation. He cited the MIRAGE study, which had shown reductions in margins and toxicity, and argued that with proper workflow organisation, MR-Linac was not more time-consuming than CBCT. He closed by challenging the very notion of the motion: “Superseded? There is nothing old or outdated about MR-Linac.”

Next came Mairéad Daly (UK), who offered a pragmatic view. While acknowledging the innovation that MR-Linac had brought, she raised concerns about its global scalability and sustainability. She presented clinical images that were affected by motion artefacts, breathing, or implants, and argued that “the best” was not always necessary. “Good enough”, she stated, was sufficient in most cases. If CBCT-oART enabled the treatment of more patients, more quickly and with fewer resources, then it was the logical choice.

Yet Lorenzo Placidi (Italy) firmly rejected this choice. He was the final speaker and responded vigorously to the previous speaker’s argument; he defended the central role played by the MR-Linac while also addressing the economic aspects. He shared real-world data from Policlinico Gemelli to highlight a steady increase in patient throughput and reduced treatment times due to ongoing software improvements. For Dr Placidi, MR-Linac was not just a precision tool—it was a platform that could be used to integrate imaging, adaptation and biological data in real time. He concluded that although CBCT and MR coexisted, only one of them set the new standard: MR-linac.

The debate clearly affected the audience's view, as the final vote delivered a surprising outcome: 51% in favour, 49% against, a near tie that perfectly reflected the complexity of the topic.

This was a fitting conclusion to a debate that showed how integration of, rather than opposition between, technologies was the true key to effective, sustainable, and patient-centred adaptive radiotherapy. Because in the end, the goal remains the same – to deliver the best possible treatment to every patient, in every setting.

 

Radiation therapist

Fondazione Policlinico Universitario “A. Gemelli” IRCCS
Rome, Italy

LinkedIn: Claudio Votta
Member of the ESTRO positioning & immobilisation focus group