# K250986: S250-FIT Proton Beam Radiation Therapy Device (S250-FIT)

- Pathway: 510(k) (Traditional)
- Applicant: Mevion Medical Systems, Inc.
- Decided: Sep 12, 2025 after 165 days
- Product code: LHN (System, Radiation Therapy, Charged-Particle, Medical)
- Device class: 2
- Regulation: 21 CFR 892.5050
- Recalls of this device: none
- Data: FDA decisions to Oct 25, 2026; recalls to Oct 12, 2026

## Lineage
Longest line of descent: 8 generations back to K872369 (1988). 16 ancestors in all.
1 later device descends from it; 1 cites it directly.
0 of 18 devices in its family (counting itself) have a Class I recall.

## Predicates on the family tree (from the FDA summary)
- K172848: MEVION S250i Proton Beam Radiation Therapy Device, Mevion Medical Systems (2017) Summary page 5.

## Most influential descendants
- K253406: S250-FIT Proton Beam Radiation Therapy Device (S250-FIT) (2026), 0 descendants of its own

## Indications for use
The MEVION S250-FIT Proton Beam Radiation Therapy Device is intended to deliver proton radiation treatment to patients with localized tumors or any other conditions susceptible to treatment by radiation. When the patient is in the fully seated position, the MEVION S250-FIT is indicated for treatment of patients with localized tumors and other conditions susceptible to treatment by radiation in the sites above the mid-chest or carina.

Source page: https://510kreport.com/device/K250986
Methodology: https://510kreport.com/methodology