The Royal Marsden NHS Foundation Trust has delivered its first online adaptive radiotherapy (OART) treatment on a conventional Elekta C-arm linear accelerator using RayStation’s module for rapid adaptive replanning.

OART adjusts a patient’s radiation plan at the treatment session based on daily imaging, allowing clinicians to reoptimize dose delivery as anatomy changes. The approach has typically been associated with specialized systems built for adaptive workflows, limiting access for many radiotherapy departments.

“Online adaptive radiotherapy on widely used C-arm linacs is a game changer, made possible entirely by software, and we are impressed by the Royal Marsden’s achievement in bringing this into clinical practice across their network of radiotherapy departments,” said Johan Löf, founder and CEO of RaySearch.
RaySearch and Royal Marsden said they plan to continue collaborating to streamline workflows, improve interoperability, and expand use across additional machine types.

Royal Marsden’s use of a widely deployed C-arm linac suggests adaptive workflows can be extended to equipment already common in hospital fleets, potentially broadening clinical availability without requiring purpose-built machines.

The London-based trust previously demonstrated online adaptation in March 2025 on an Accuray Radixact system using RayStation and has since used that platform for routine online adaptive treatments. Royal Marsden’s Radixact system and RayStation were funded by The Royal Marsden Cancer Charity.

RaySearch, the Stockholm-based radiotherapy software developer, said the Elekta treatment used the same underlying adaptive principles as the Radixact workflow. The company characterized the result as evidence that the adaptive replanning module can transition between delivery systems and support the timing demands of on-table replanning.

The first treatment took place in December 2025.

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