BEUDAMED
    FDA Adverse Event Summary report: N

    CLINAC LINEAR ACCELERATOR

    MDR report key: 20585 · Received March 23, 1995

    Report

    Report Number
    MW1005544
    Date Received
    March 23, 1995
    Report Date
    March 22, 1995
    Manufacturer
    VARIAN ASSOCS., INC.
    Product Code
    IYE
    Report Source
    Voluntary report
    Reporter Location
    WI, US
    Reporter Occupation
    PHYSICIST

    Narratives

    Description of Event or Problem · 1

    A PT WAS TREATED WITH THE 6 MV X-RAY BEAM AND 15 DEGREE WEDGE OF A LINEAR ACCELERATOR USING MONITOR UNITS COMPUTED FOR THE 6 MV X-RAY BEAM AND 15 DEGREE WEDGE OF A DIFFERENT LINEAR ACCELERATOR. THIS RESULTS IN A 5% UNDERDOSE TO THE PT PER TREATMENT FOR 24 OUT OF 42 TREATMENTS ALTHOUGH THE ERROR COULD HAVE BEEN MUCH MORE SIGNIFICANT (25-30%) HAD 30 OR 45 DEGREE WEDGES BEEN USED. THE 5% ERROR IN DOSE IS PRIMARILY DUE TO THE DIFFERENCE IN WEDGE TRANSMISSION FACTORS OWING TO DIFFERENT WEDGE DESIGNS USED ON THE TWO LINACS. (THE DEPTH DOSE CHARACTERISTICS OF THE TWO MACHINES ARE SIMILAR.) THE PROBLEM REPRESENTS A RARE FAILURE OF CO SYSTEM OF INTERNAL QA CHECKS. IT COULD POSSIBLY BE AVOIDED BY 1) USE OF A RECORD-AND-VERIFY SYSTEM (AN EXPENSIVE OPTION THAT HOSP DO NOT YET HAVE AT ITS INSTITUTION) OR 2) BY REPLACING THE WEDGES OF THE OLDER DEVICE WITH THOSE OF THE NEWER DEVICE WHICH SHOULD RESULT IN SIMILAR WEDGE TRANSMISSION FACTORS FOR THE NEARLY IDENTICAL 6 MV X-RAY BEAMS. THE MFR HAS BEEN CONTACTED REGARDING THE LATTER OPTION. (ALSO SEE 1005552.)

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    1 CLINAC LINEAR ACCELERATOR LINEAR ACCELARATOR IYE VARIAN ASSOCS., INC. 6-100

    Patients

    Seq Age Sex Outcome Treatment
    1 *