BEUDAMED
    FDA Adverse Event Malfunction Summary report: N

    PRECISE SERIES LINAC

    MDR report key: 5018053 · Received August 20, 2015

    Report

    Report Number
    9617016-2015-00011
    Event Type
    Malfunction
    Date Received
    August 20, 2015
    Report Date
    May 20, 2016
    Manufacturer
    ELEKTA LTD
    Product Code
    IYE
    PMA / PMN Number
    K051932
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    UK
    Reporter Occupation
    OTHER

    Narratives

    Additional Manufacturer Narrative · 1

    PRELIMINARY INVESTIGATION OF THE FAILURE MODES HAVE ESTABLISHED THAT THE WELDS WILL NOT FAIL CATASTROPHICALLY DUE TO THE TOTAL LOADING BUT MAYBE SUBJECT TO FATIGUE. FATIGUE OF THE WELDS WILL RESULT IN CRACKS AND POTENTIAL FULL STRUCTURAL FAILURE OF THE WELD BUT ONLY AFTER MANY STRESS CYCLES. A STRESS CYCLE WOULD OCCUR AFTER EACH REVOLUTION OF THE GANTRY. THIS MAY RESULT IN AN INCREASE IN DEFLECTION OF THE ARM MOUNTING BRACKETS RESULTING IN AN ISO-CENTER SHIFT. THE ACTUAL DEFLECTION WITH THIS FAILURE IT IS PREDICTED TO BE LESS THAN A FEW MILLIMETRES HOWEVER IT IS UNKNOWN AT THIS TIME AND FURTHER INVESTIGATION IS ONGOING. THE RISK OF INJURY OCCURRING TO PATIENTS, CLINICAL USERS OR SERVICE USERS HAVE BEEN ASSESSED AS INCREDIBLE DUE TO THE MAIN STRUCTURES INTEGRITY WILL REMAIN INTACT AND PREVENT THE ARM, WEIGHT STACK OR OTHER STRUCTURES FROM FALLING AND THE SYSTEM WOULD REMAIN BALANCED.

    Additional Manufacturer Narrative · 1

    THE MANUFACTURER'S INVESTIGATION IS ONGOING. FURTHER DETAILS WILL BE PROVIDED IN THE FINAL REPORT ONCE THE INVESTIGATION HAS BEEN COMPLETED.

    Additional Manufacturer Narrative · 1

    THE MANUFACTURER'S INVESTIGATION IS ONGOING. THIS IS THE SECOND FOLLOW-UP REPORT. THE MANUFACTURER'S WELD CALCULATIONS CONSIDERED A WORST CASE WELD (WELD LEG LENGTH OF 3MM, LOW QUALITY AND HIGHEST STRESS LOCATION) USING CONSERVATIVE INDUSTRY PRACTISES TO DETERMINE THE STRESS WITHIN THE WELD. USING THE RESULTING STRESS AND KNOWN DUTY CYCLE OF THE LINAC, AN ESTIMATE OF WELD FATIGUE LIFE WAS MADE. IT WAS DETERMINED THAT THERE WOULD BE A VERY LOW RISK OF EARLY FATIGUE CRACKING, THEREFORE NO IMMEDIATE FIELD SAFETY CORRECTIVE ACTION IS REQUIRED. ALL ELEKTA AND SUPPLIER HELD STOCK HAS BEEN INSPECTED WITH THE ASSISTANCE OF THE (B)(4) AND WHERE NECESSARY, STOCK HAS BEEN QUARANTINED. THE QUARANTINED STOCK MAY BE REWORKED ACCORDING TO AN APPROVED WELD REWORK PROCEDURE, PENDING FURTHER INVESTIGATIONS OF OTHER AFFECTED SPECIFICATIONS FROM THE ADDITIONAL WELDING PROCEDURE. ALL NEW STOCK HAS BEEN MANUFACTURED TO SPECIFICATION AND IS BEING INSPECTED ACCORDING TO RECOMMENDATIONS FROM THE (B)(4). HAVE CONDUCTED TESTS ON WELD STRENGTHS FOR THE MANUFACTURER. LIFE TESTING IS ESTIMATED TO BEGIN END OF FEBRUARY 2016. THE LIFE TESTING WILL INVOLVE TWO FULLY REPRESENTATIVE LINACS THAT WILL BE RUN AT AN ACCELERATED RATE FOR A REPRESENTATIVE CLINICAL SERVICE LIFE (EQUIVALENT OF 15 YEARS). IT IS EXPECTED THAT THE LIFE TEST WILL TAKE A MINIMUM OF 60 DAYS TO COMPLETE. ONE LINAC WILL HAVE THE WORST WELD SIZE AND QUALITY COMBINATION THAT WERE INSPECTED WHILST THE OTHER LINAC WILL HAVE WELDS THAT ARE UNDER THE SPECIFIED SIZE BUT HAVE BEEN DEEMED FIT FOR PURPOSE. AN UPDATE ON THE INVESTIGATION WILL BE PROVIDED IN THE NEXT REPORT.

    Additional Manufacturer Narrative · 1

    LIFECYCLE TESTING IS CURRENTLY ONGOING AT AN ELEKTA TESTING FACILITY. THE TESTING IS DESIGNED TO IMITATE A 'WORST CASE' SCENARIO OVER A 15 YEAR LIFE OF THE MACHINE, THIS IS DUE TO BE REVIEWED IN 2-3 MONTHS. ANY FURTHER ACTION WILL BE BASED ON THE RESULTS OF THIS TESTING, WHICH WILL FOLLOW NORMATIVE FIELD ACTION PROCESSES. NO IMMEDIATE FIELD SAFETY CORRECTIVE ACTION CURRENTLY REQUIRED. RISK ASSESSMENT: SEVERITY MAJOR. IF THE WELD WAS TO FAIL THERE WOULD BE AN INCREASE IN DEFLECTION OF THE ARM MOUNTING BRACKETS RESULTING IN AN ISO-CENTRE SHIFT. THE ACTUAL DEFLECTION WITH THIS FAILURE IT IS PREDICTED TO BE LESS THAN A FEW MILLIMETRES HOWEVER IT IS UN CONFIRMED AT THIS TIME, RESULTING IN A SEVERITY OF MAJOR IN THE CASE STEREOTACTIC AND SIMILAR THERAPIES LIKELIHOOD OF HARM IMPROBABLE. THE PURPOSE OF THE SUPPORT BRACKETS IS TO PREVENT DEFLECTION AND INCREASE THE STRUCTURES RESISTANCE TO FATIGUE. IF THE WELDS IN QUESTION WERE INSUFFICIENT AND FAILED, THE MAIN STRUCTURES INTEGRITY WILL REMAIN INTACT AND PREVENT THE ARM, WEIGHT STACK OR OTHER STRUCTURE FROM FALLING AND THE SYSTEM WOULD REMAIN BALANCED. PREVIOUS ACCELERATED LIFE TESTING OF A SYSTEM THAT WAS TO SPECIFICATION RESULTED IN AN EQUIVALENT CLINICAL LIFE OF APPROXIMATELY 34 YEARS WITH THE WELDS IN QUESTION SHOWING NO CRACKING. ADDITIONALLY QA CHECKS AND AUDIBLE NOISE FROM CRACKS IN THE WELD WOULD REDUCE THE LIKELIHOOD OF A MISTREATMENT. A MAJOR X IMPROBABLE RISK CALCULATION PROVIDES US WITH A TOLERABLE RISK.

    Description of Event or Problem · 1

    THE MANUFACTURER HAS INTERNALLY IDENTIFIED A SUPPLIER ERROR WHERE SOME WELDS ON THE GANTRY DRUM STRUCTURE WERE SUPPLIED NOT TO SPECIFICATION. THESE WELDS ATTACH SUPPORT BRACKETS TO THE MAIN FIXING STRUCTURE FOR THE WEIGHT STACK AND THE FRONT ARM MOUNTING. THE SUPPLIER OF THE DRUM HAS IDENTIFIED A CHANGE OF PROCESS THAT RESULTED IN THE NOT TO SPECIFICATION WELDS. AS SUCH THE SERIAL NUMBERS OF THE 34 AFFECTED DRUMS ARE KNOWN, 16 OF THE 34 DRUMS HAVE LEFT THE MANUFACTURER WITH THE REMAINING 18 PLACED IN QUARANTINE.

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    551620 PRECISE SERIES LINAC ACCELERATOR, LINEAR MEDICAL, PRODUCT CODE: IYE IYE ELEKTA LTD

    Patients

    Seq Age Sex Outcome Treatment
    1 Other