# Upright radiotherapy positioning (Leo Cancer Care Marie, P-Cure, Mevion S250-FIT)

Source: https://onco.cc/technologies/upright-radiotherapy-positioning/  
OnCo record `upright-radiotherapy-positioning` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Instead of lying on a couch under a rotating machine, the patient sits or perches on a chair that turns in front of a fixed beam. Because the heavy beam line no longer has to rotate, a proton machine can fit in an ordinary radiotherapy room.

## Summary

A rotating gantry is the largest and most expensive part of a proton centre. Upright systems remove it: the beam stays horizontal and a robotic chair rotates and tilts the patient in front of it, with an upright CT scanner for imaging in the treatment position. P-Cure's proton system was cleared by the FDA on 20 March 2023 (K221996) as a synchrotron with a single fixed beam and a seated patient, for the head, neck and thorax; its 2025 clearance (K242418) allows seated or supine treatment. Leo Cancer Care's Marie positioning and imaging system was cleared on 25 July 2025 (K250970) for treatment in the "upright position rather than conventional supine treatments", with its Eve patient positioner cleared in 2024 (K231612), and was CE-marked in May 2026. Mevion combined Marie with its compact cyclotron in the S250-FIT, cleared on 12 September 2025 (K250986); the 510(k) summary limits fully seated treatment to "sites above the mid-chest or carina". Mevion states that the system fits "a standard 110 m² (1,200 sq ft) LINAC vault", and the first patient was treated at Stanford in June 2026.

Upright treatment is old in fixed-beam particle rooms and in some photon work, but it needs imaging in the upright position because organs sit differently when a person sits. The open questions are which sites it suits beyond the head, neck and upper chest, how reproducible daily set-up is, and whether patients who struggle to lie flat (with breathing difficulty, pain or swallowing problems) find it easier; no randomised comparison with supine treatment was found.

## Fields

- Kind: Technology
- Status: emerging
- Last checked: 2026-11-04
- Also known as: Upright radiotherapy; Seated proton therapy; Marie upright positioning system; Leo Cancer Care Marie; S250-FIT
- Tags: machines-wave3
- Principle: A fixed horizontal beam treats a patient who is rotated and tilted by a robotic chair; an upright CT or radiographic imager images the patient in the treatment position so the plan matches the seated anatomy.
- Since: 2023
- Strengths: Removes the rotating gantry, the largest cost and space item of a proton room; May suit patients who cannot lie flat; Proton therapy in a room the size of a linac bunker (maker's statement)
- Limitations: Cleared indications concentrate on the head, neck and thorax when seated; Anatomy shifts between seated and supine positions, so planning must use upright imaging; No randomised comparison with supine treatment found

## Sources

- FDA 510(k) K221996: P-Cure Proton Beam Therapy System (20 March 2023): https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm?ID=K221996
- FDA 510(k) K242418: P-Cure Proton Therapy System, seated or supine (12 May 2025): https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm?ID=K242418
- FDA 510(k) K250970: Leo Cancer Care Marie (25 July 2025): https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm?ID=K250970
- FDA 510(k) K231612: Leo Cancer Care Eve patient positioner (7 May 2024): https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm?ID=K231612
- FDA 510(k) K250986: Mevion S250-FIT (12 September 2025): https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm?ID=K250986
- Leo Cancer Care secures CE mark for Marie (press release, 20 May 2026): https://www.placera.se/pressmeddelanden/leo-cancer-care-secures-ce-mark-for-marie-advancing-upright-radiotherapy-in-europe-20260520
- Mevion: the S250-FIT, a proton therapy system designed for a linac vault (press release, May 2026): https://mevion.com/press-release/mevion-introduces-the-first-proton-therapy-system-designed-for-a-linac-vault-at-estro-2026
- Mevion: first patient treated on the S250-FIT at Stanford (press release, June 2026): https://mevion.com/press-release/stanford-first-patient-s250-fit

## Connected records

- ideas: [A shared registry comparing upright and lying-down radiotherapy](https://onco.cc/ideas/idea-mach-upright-versus-supine-registry/), [Compact FLASH and proton systems at the price of a conventional linac](https://onco.cc/ideas/idea-moon-compact-flash-proton/)
- cancers: [Brain metastases (secondary brain tumours)](https://onco.cc/cancers/secondary-brain-tumours/), [Head and neck squamous cell carcinoma](https://onco.cc/cancers/head-and-neck/), [Non-small-cell lung cancer](https://onco.cc/cancers/nsclc/), [Oesophageal cancer](https://onco.cc/cancers/esophageal/)
- fronts: [Devices & Physical Therapies](https://onco.cc/fronts/devices/), [Radiation Therapy](https://onco.cc/fronts/radiation/)
- technologies: [Carbon-ion synchrotrons and facilities](https://onco.cc/technologies/carbon-ion-synchrotrons/), [Proton therapy](https://onco.cc/technologies/proton-therapy/), [Proton therapy machines: cyclotrons, synchrotrons and single-room systems](https://onco.cc/technologies/proton-therapy-systems/)
- companies: [Leo Cancer Care](https://onco.cc/companies/leo-cancer-care/), [Mevion Medical Systems](https://onco.cc/companies/mevion/), [P-Cure](https://onco.cc/companies/p-cure/), [RaySearch Laboratories](https://onco.cc/companies/raysearch/)
- institutions: [Stanford Health Care / Stanford Cancer Institute](https://onco.cc/institutions/stanford/)
- roadmaps: [Particle therapy machines: from Loma Linda to proton rooms in a linac vault, carbon gantries and FLASH](https://onco.cc/roadmaps/particle-therapy-machines-roadmap/)

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