First proton therapy system designed to fit into an existing LINAC vault, advancing access to high-quality proton therapy

Mevion Medical Systems today announced that the U.S. Food and Drug Administration (FDA) has granted 510(k) clearance for the MEVION S250-FIT™ Proton Beam Radiation Therapy System, marking a significant milestone in expanding access to proton therapy. 

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The MEVION S250-FIT Proton Therapy System

The MEVION S250-FIT is the first and only proton therapy system designed to seamlessly fit into a standard radiation therapy vault. By leveraging existing infrastructure, the MEVION S250-FIT system lowers barriers for hospitals and cancer centers to adopt proton therapy, accelerating access and bringing advanced, high-quality proton therapy closer to patients worldwide.

The MEVION S250-FIT is currently under installation at Stanford Health Care and BayCare Health System, with additional installations beginning at Atlantic Health System and the University of Nebraska Medical Center. This momentum underscores how top-tier institutions are embracing the MEVION S250-FIT system as a future-ready, quality-driven solution, reaffirming Mevion’s role as the trusted partner of leading cancer centers.

“The FDA clearance of the MEVION S250-FIT marks the beginning of a new era in proton therapy. For more than two decades, Mevion has redefined proton therapy through audacious innovation -- from pioneering the world’s first compact, single-room system to now enabling proton therapy to fit into existing radiation therapy vaults, expanding access for patients worldwide. I am incredibly proud of the Mevion team and our partners at Leo Cancer Care for making this achievement possible and look forward to the impact of this innovation as centers like Stanford bring it to patients.” — Tina Yu, CEO and President of Mevion Medical Systems.

The MEVION S250-FIT system extends Mevion’s leadership in compact proton therapy by combining industry-leading precision, efficiency, and adaptability. Building on Mevion’s HYPERSCAN^® pencil beam scanning platform and introducing DirectArc™ proton arc therapy, the FIT system is also FLASH research ready, ensuring cancer centers gain advanced capabilities today while staying ready for future innovations.

Mevion will be showcasing the MEVION S250-FIT and its latest innovations at the ASTRO 2025 Annual Meeting in San Francisco, September 28–30 at booth #1215.

About Mevion Medical Systems

Mevion Medical Systems is the global leader in compact proton therapy, dedicated to advancing accessibility of high-quality cancer care. Founded in 2004 by pioneers from Mass General and MIT, Mevion pioneered the world’s first single-room proton therapy system and continues to set the standard for precision, efficiency, and adaptability in proton treatment. Cancer centers worldwide rely on Mevion’s groundbreaking systems—including the MEVION S250i^® and MEVION S250-FIT™ with HYPERSCAN^® pencil beam scanning and DirectArc™ proton arc therapy—to deliver precise, life-changing care. Headquartered and manufactured in Littleton, Massachusetts, with a presence in Europe and Asia, Mevion provides unmatched reliability, service, and innovation to ensure cancer centers worldwide can deliver the highest-quality proton therapy with confidence. For more information, please visit http://www.mevion.com.

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