Upright proton therapy arrives at the American Society for Radiation Oncology 2026 Annual Meeting with more attention on it than any prior year, and there is no more fitting place for that conversation than Boston, where proton therapy began as an idea. This year, that conversation is grounded in something new: patients are being treated upright. Stanford Medicine reported the first patient treated upright on a MEVION S250-FIT Proton Therapy System™ with Leo Cancer Care’s Marie® upright positioning and imaging solution and RayStation treatment planning on June 4, 2026 – integrated within a standard radiation therapy vault.
Mevion Medical Systems, Leo Cancer Care and RaySearch Laboratories, the technology pioneers behind that milestone, will be at the forefront of this year’s Annual Meeting of the American Society for Radiation Oncology, where attendees can see the upright positioning system, sit in it, and speak with the therapists and physicists who position patients upright today.
Boston’s relationship with proton therapy is not just deep – it is foundational. In 1946, Harvard physicist Robert R. Wilson proposed using the Bragg peak to treat cancer, planting the seed for an entirely new field of medicine. Fifteen years later, Harvard’s cyclotron and Massachusetts General Hospital began treating patients together, a partnership that ran four decades and led the field’s early development. In 2004, Mevion Medical Systems was founded in Massachusetts with a singular mission: to make proton therapy accessible to every health system.
That mission produced a breakthrough in 2012, when the MEVION S250 Proton Therapy System® received FDA clearance as the world’s first compact proton therapy system – and again in 2025, when the MEVION FIT™ , the first proton therapy system designed to fit within an existing LINAC vault, received FDA clearance. Now, as ASTRO 2026 convenes in the city where it all began, upright proton therapy stands as the next landmark chapter in that history.
For radiation oncology departments, integrated proton therapy represents a next step in the evolution of treatment capability. Departments have incorporated IGRT, IMRT, and VMAT into practice. Integrating protons extends that conversation to another treatment option within the radiation oncology service, delivered by the team already there, in a vault they already have.
Designed for installation in a standard radiation therapy vault, FIT™ gives health systems a way to evaluate proton therapy within existing infrastructure. That creates a route for community programs and for academic centers with limited room to expand. There are about a dozen FIT™ systems in development across the world.
“Every health system should be able to offer proton therapy as part of its radiation oncology service,” said Tina Yu, PhD, President and CEO of Mevion Medical Systems. “With patients being treated in an existing department, the conversation can finally focus on how proton therapy fits into a health system’s clinical service, facilities and capital planning.”
FIT combines Mevion’s ultra-compact proton accelerator and HYPERSCAN® pencil beam scanning technology with Leo Cancer Care’s Marie® 360-degree upright patient positioning system and integrated CT imaging, and is powered by RaySearch Laboratories’ RayStation® treatment planning system. Together, these technologies create an integrated platform for proton therapy within a compact radiation oncology environment.
The system also incorporates Mevion’s Adaptive Aperture for beam shaping at the patient. At ASTRO, teams can discuss future solutions such as DirectARC™ proton arc therapy and adaptive workflows.
Leo Cancer Care has led the development of upright patient positioning and imaging across radiation therapy, with systems in clinical and research use internationally and a published body of work on positioning reproducibility, imaging in the treatment posture, and patient experience.
“Our work is to help clinical teams bring upright imaging and positioning into daily practice,” said Stephen Towe, CEO of Leo Cancer Care. “At ASTRO, we want therapists, physicists and physicians to experience the setup and discuss the practical questions that matter in their departments.”
RaySearch Laboratories is leading the development of treatment planning for particle therapy, with RayStation used at the majority of particle therapy centers worldwide. For upright delivery, that work extended dose calculation and plan optimization to the upright treatment geometry, and RayStation is now in clinical use for upright proton therapy at Stanford Medicine.
“We are proud to have contributed to the first proton treatments at Stanford Medicine together with Mevion and Leo Cancer Care,” said Johan Löf, Founder and CEO of RaySearch Laboratories. “Through the close integration of the three systems, we have shown that RaySearch’s advanced and well-established proton therapy algorithms deliver high performance also when treating patients in the upright position.”
Clinical Experience at ASTRO
ASTRO’s scientific program includes three Stanford‑led posters drawn directly from their clinical experience with upright therapy, addressing clinical integration, pediatric upright treatment and anesthesia integration, and proton delivery workflows.
That clinical momentum sets the stage for what promises to be the most concentrated week of upright therapy programming to date. The week opens on Friday, September 25 with The Upright RT Summit, a user meeting hosted by Leo Cancer Care for institutions adopting the upright solution across multiple modalities – a half‑day meeting on where upright radiation therapy stands and where it is going, spanning early clinical experience, research, immobilization and pediatric applications, and a technology and integration roadmap.
On Saturday, September 26, the Dana‑Farber Proton Therapy Symposium will explore integration of upright proton therapy into multidisciplinary cancer care. That afternoon, the “Inside Proton Innovation” experience at Mevion’s Littleton, MA headquarters will cover treatment planning, adaptive workflows, upright positioning and manufacturing.
The conversation continues on the show floor. Attendees can visit Mevion at booth #2117, Leo Cancer Care at booth #519 and RaySearch at Booth #724. At the Mevion and Leo Cancer Care booths, attendees can experience upright positioning firsthand and sit in the system. At the RaySearch booth, attendees can view the creation of MEVION FIT treatment plans in RayStation. Mevion will host a Meet the Experts program right inside the booth Sunday through Tuesday, with physicians, physicists and therapists discussing clinical practice and departmental integration.
The momentum extends beyond ASTRO. Patients are being treated, clinical teams are sharing what they have learned, and health systems now have a concrete example of proton therapy integrated into an existing department. For Mevion, Leo Cancer Care and RaySearch, the goal is straightforward: to put proton therapy in reach for as many health systems and patients as possible.
About Mevion Medical Systems
Mevion Medical Systems is a leading provider of compact proton therapy systems for cancer care. Dedicated to advancing the design and accessibility of proton therapy worldwide, Mevion pioneered the single-room platform and continues to further the science and application of proton therapy. Since 2013, Mevion compact proton therapy single-room systems have been used by leading cancer centers for treating patients. Mevion’s series of products, including the flagship MEVION S250i® and MEVION S250-FIT™ with HYPERSCAN® pencil beam scanning, represent the world’s most compact proton therapy systems that eliminate the obstacles of size, complexity, and cost. Mevion is headquartered in Littleton, Massachusetts with a presence in Europe and Asia. For more information, please visit www.mevion.com
About Leo Cancer Care
Leo Cancer Care is challenging the conventional delivery of radiotherapy through an upright approach that places the patient at the center of treatment. Its Marie® solution combines 360-degree upright patient positioning with integrated CT imaging and can be paired with a fixed particle beam. By removing the need for a large rotating gantry, the technology is designed to reduce the space and infrastructure required for advanced radiotherapy while supporting a more natural and patient-focused treatment experience.
For more information, visit leocancercare.com.
About RaySearch Laboratories
RaySearch Laboratories AB (publ) is a medical technology company that develops innovative software solutions for improved cancer treatment. RaySearch markets the RayStation®* treatment planning system (TPS) and the oncology information system (OIS) RayCare®*. The most recent additions to the RaySearch product line are RayIntelligence®*. RayIntelligence is an oncology analytics system (OAS) which enables cancer clinics to collect, structure, and analyze data. RaySearch’s software has been sold to over 1,200 clinics in 54 countries. The company was founded in 2000 as a spin-off from the Karolinska Institute in Stockholm and the share has been listed on Nasdaq Stockholm since 2003 (STO: RAY B). More information is available at raysearchlabs.com
*RaySearch Products are subject to regulatory clearance in some markets.
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