Food, drugs, devices › Mevion Medical Systems, Inc.

Device recall: MEVION S250 Product Usage: Proton Radiation Therapy System

FDA enforcement event 75494 · Class II · initiated 20 Oct 2016 · status Terminated · terminated 15 May 2017

DeviceVoluntary: Firm initiated1 product recordLittleton, MA

Mevion Medical Systems, Inc. (Littleton, MA) initiated this device recall on 20 Oct 2016; FDA lists 1 product record under event 75494, classified Class II.

FDA defines Class II as a situation in which use of or exposure to a violative product may cause temporary or medically reversible adverse health consequences or where the probability of serious adverse health consequences is remote. 91% of the 1,232 device enforcement events initiated in 2016 carry the same class.

Status: Terminated, terminated 15 May 2017. Initiation: voluntary: firm initiated. Mevion Medical Systems, Inc. has 14 enforcement events on this register, with a median of 1 product record per event.

Recall classification reflects the relative degree of health hazard. Text in quotation marks is FDA's. openFDA export dated 28 Sep 2026.

Recalling firm

Mevion Medical Systems, Inc., Littleton, MA.

Reason for recall

"Software defect:2D projection of contours in Verity. The defect causes structures to appear off from their true position in the DRR and the radiograph with an error that increases with the distance of the structure from isocenter"

Distribution

"US Nationwide Distribution in the states of: FL, MO, NJ, OH, OK"

Product records

Recall number	Product	Quantity	Class	Status	Report date
Z-0411-2017	MEVION S250 Product Usage: Proton Radiation Therapy System	6 units	Class II	Terminated	23 Nov 2016

Context

91%of 2016 device events are Class II1,232 events that year

1product record in this eventfirm median: 1

14events on this register for the firm

Other enforcement events for Mevion Medical Systems, Inc.

Initiated	Product (first record)	Type	Class	Records
1 Feb 2022	Mevion S250 and S250i Proton Therapy Systems hand pendant (P/N 10263 or P/N 37808)	Device	Class II	1
19 Oct 2020	MEVION S250i, MEVION S250; Proton Radiation Treatment System - Product Usage: intended to deliver proton radiation treat	Device	Class II	1
23 Jun 2020	MEVION S250 Proton Radiation Treatment System; intended to deliver proton radiation treatment to patients	Device	Class II	1
15 May 2020	MEVION S250i, MEVION S250; Proton Radiation Treatment System	Device	Class II	1
1 Oct 2018	MEVION S250i	Device	Class II	1
29 Jun 2018	MEVION S250/MEVION S250i Proton Beam Radiation therapy system Product Usage: Indicated for the delivery of radiation for	Device	Class II	1
16 Dec 2016	MEVION S250-Proton Radiation Therapy Product Usage: Proton Radiation Therapy	Device	Class II	1
31 Oct 2016	MEVION S250 Product Usage: Proton Radiation Therapy	Device	Class II	1
21 Oct 2016	MEVION S250 Product Usage: Proton Radiation Therapy System	Device	Class II	1
15 Mar 2016	MEVION S250 for Proton Radiation Therapy	Device	Class II	1

All 14 events for Mevion Medical Systems, Inc.

Questions and answers

Why was this device recalled?

FDA's record gives the reason for recall as: "Software defect:2D projection of contours in Verity. The defect causes structures to appear off from their true position in the DRR and the radiograph with an error that increases with the distance of the structure from isocenter"

What does Class II mean?

FDA classifies recalls by relative degree of health hazard. Class II is a situation in which use of or exposure to a violative product may cause temporary or medically reversible adverse health consequences or where the probability of serious adverse health consequences is remote.

Where was the product distributed?

FDA's distribution pattern field reads: "US Nationwide Distribution in the states of: FL, MO, NJ, OH, OK"

Is the recall still ongoing?

FDA lists the status as Terminated; the termination date is 15 May 2017. "Terminated" means FDA has determined that all reasonable efforts to remove or correct the product have been made.

Where does this data come from?

openFDA enforcement reports (food, drug and device), CC0, export dated 28 Sep 2026. Text in quotation marks is FDA's. The FDA enforcement report linked above is authoritative.

Provenance

Source: openFDA device enforcement reports (CC0), export dated 28 Sep 2026; records grouped by FDA event number. The class shown for the event is the most severe class among its records. Errors in processing are corrected at the next build; see corrections.