MAUDE Adverse Event Report: ELEKTA INC MOSAIQ; ACCELERATOR, LINEAR, MEDICAL

Lot Number	2.83.053
Medical Device Problem Code	Computer Software Problem (1112)
Health Effect - Clinical Code	Insufficient Information (4580)
Date of Event	12/22/2025
Type of Reportable Event	Serious Injury
Additional Manufacturer Narrative
H4: manufacturing date is not on the label, but it is known so field h4 has been completed with this information.The manufacturer's investigation is on-going and further information will be provided once the investigation has completed.
Event or Problem Description
The customer reported that a patient received treatment twice on the same arc.
Additional Manufacturer Narrative
H11: updated: the investigation was completed by conducting a thorough evaluation of the product and the reported information.The customer reported that a patient received treatment twice on the same arc.The logs for (b)(6) 2025, show that field arc1 was entered for treatment verification at 15:33:37.The terminate key was turned by the user to stop treatment after 160.7 mu was administered.Treatment resumed at 15:40:02 and 575.1 mu more were given before a "table height servo" error ended delivery again.At this point, arc1 had received a total of 735.8 mu of the prescribed 953.4 mu.The remaining 217.6 mu was given later around 15:58 to complete the prescribed daily dose to field arc1.The treatment was recorded in mosaiq.After this, at 15:59:29, the field arc1 was selected once more from the treatment delivery table.The user was presented with a warning that the field had already been treated today and chose yes to continue.Moreover, the user received a fractional dose warning then proceeded to override the fractional dose to move forward with another full treatment of 953.4 mu to arc1.Field arc1 was treated twice on (b)(6) 2025.In this incident an arc was delivered two times in one day instead of the intended single time.The delivered dose from the arc was 3.11 gy.The total intended daily dose was 6.0 gy.The total intended number of fractions was 10.The remaining 9 fractions were delivered as originally planned.The error represents an ~52% overdose on the day of the incident and a 5.2% overdose over the course of the treatment.Elekta physics have assessed this as a serious radiation overdose.Mosaiq worked as intended.The root cause is abnormal use.

• Brand Name: MOSAIQ
• Common Device Name: ACCELERATOR, LINEAR, MEDICAL
• Manufacturer (Section D): ELEKTA INC; 100 mathilda place; 5th floor; sunnyvale CA 94086
• Manufacturer (Section G): ELEKTA SOLUTIONS AB; 400 perimeter center terrace; suite 50; atlanta GA 30346
• Manufacturer Contact: cornerstone; london road; crawley, west sussex RH10 -9BL
• MDR Report Key: 24113556
• Report Number: 2950347-2026-00002
• Device Sequence Number: 14971348
• Product Code: IYE
• UDI-Device Identifier: 00858164002367
• UDI-Public: (01)00858164002367(10)2.83.053
• Combination Product (Y/N): N
• Initial Reporter Country: IT
• PMA/510(K) Number: K183034
• Number of Events Summarized: 1
• Summary Report (Y/N): N
• Serviced by Third Party (Y/N): Unknown
• Reporter Type: Manufacturer
• Report Source: Other,Foreign,Health Professional,User Facility
• Initial Reporter Occupation: Other Health Care Professional
• Type of Report: Initial,Followup
• Report Date (Section B): 02/06/2026

1 Device was Involved in the Event

1 Patient was Involved in the Event

• Is this an Adverse Event Report?: Yes
• Is this a Product Problem Report?: No
• Operator of Device: Health Professional
• Device Lot Number: 2.83.053
• Was Device Available for Evaluation?: Yes
• Is the Reporter a Health Professional?: Yes
• Type of Report(Section G): Thirty-Day
• Initial Date Received by Manufacturer: 12/22/2025
• Supplement Date Received by Manufacturer: Not provided
• Initial Report FDA Received Date: 01/20/2026
• Supplement Report FDA Received Date: 02/06/2026
• Was Device Evaluated by Manufacturer? (Y/N): Yes
• Date Device Manufactured: 08/31/2021
• Is the Device Labeled for Single Use? (Y/N): No
• Usage of Device: Reuse
• Patient Sequence Number: 1
• Outcome Attributed to Adverse Event: Other
• Patient Sex: Unknown