The investigation was completed by conducting a thorough evaluation of the product and the reported information.The customer was performing linac beam delivery tests after a mosaiq upgrade.After the treatment beam was started, the customer interrupted the beam and moved a geometric position.Once beam on is initiated, mosaiq can no longer verify geometrical positions as mosaiq would not be able to keep up with the change in positions of the gantry or mlc leaves.If mosaiq tried to verify, it would result in continuous stoppage of delivery.When the beam is interrupted whilst it is on, the interface does not provide communication between the machine and mosaiq and an inhibit is not raised.Mosaiq did not have any malfunction and was working as designed and intended.The root cause was determined to be use error since there was an unintentional movement after completing the setup correctly and the device had been beamed on.No patients were involved during the test that the customer performed.
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