October 22, 2021 — RaySearch Laboratories AB and Mevion Medical Systems, two companies that are leading the field of proton therapy, announce a collaboration to develop advanced treatment planning techniques for FLASH delivery with the MEVION S250i Proton Therapy System.
The collaboration will explore FLASH intensity modulated proton therapy (IMPT) delivery using a technique that supports the delivery of large-volume clinical FLASH fields through the combination of smaller fields, each delivered at FLASH dose rates which complements Mevion’s advanced Hyperscan delivery system.
Townsend Zwart, Vice President of Advanced Development, Mevion Medical Systems, says: “Mevion is pleased to continue our long partnership with RaySearch to develop ultra-high dose rate (FLASH) intensity modulated proton therapy. Optimizing FLASH delivery requires explicit consideration of the time dependent dose delivery and sequencing of proton spots. Overlapping spots or spots with multiple pulses may have complex FLASH weighting factors. Differing tissue types or tissue properties may also need to be included in an effective dose weighting model. The RaySearch development team is uniquely qualified to incorporate these features into a FLASH dose calculation module.”
Kjell Eriksson, Chief Science Officer, RaySearch, says: “RayStation already supports IMPT planning for Mevion’s Hyperscan system with Monte Carlo dose calculation for both optimization and final dose calculation. We are now excited to explore how RayStation can create optimal FLASH plans for the Hyperscan system and to further deepening our partnership.”
Since 2014, RaySearch and Mevion have collaborated to provide advanced treatment planning capabilities for Mevion’s HYPERSCAN pencil-beam scanning and Adaptive Aperture pMLC. Both companies will be exhibiting at the upcoming American Society for Radiation Oncology (ASTRO) annual meeting in Chicago, October 24–26. Attendees are invited to the respective booths to learn more.
* FLASH therapy is currently under preclinical research and is not yet available for commercial sale or clinical use.
For more information: www.mevion.com
September 29, 2026 
