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Siemens conducted a detailed investigation of the reported event.The investigation was performed on expert discussions (considering complaint description, cs reports, system history, system log files).The detailed investigation revealed that the cause of the blocked x-ray release was a temporary problem in the internal signal processing.In regular intervals the hardware is checked automatically.Within this check the signal line between relevant sensors and the evaluation component is tested.The test is triggered when a relay switches the contact to the sensors off and back on.The d1-board (evaluation component) detects the falling edge and checks that the voltage drops below a defined "low" level and remains like that for a defined, short period of time.In the present case, it was found that the contact of the relay showed bounce effects/voltage fluctuations.This triggered multiple, successive falling edges that repeated the cable test.However, since the voltage must remain in the "low" state for a certain time for the test to pass, this caused the test to fail even though there was no fault on the signal line.As a result, the x-ray release was prevented for plane a to avoid possible severe damage to the x-ray tube.In this case the error occurs in plane a of a biplane system, x-ray will be blocked in plane a and bypass mode will be activated, which leads to blocking x-ray in plane b.Normal operation of the system was restored by a "power cycle," i.E., the system was shut down and turned back on so that the associated components (x-ray generator, tube) were restored to normal.Field update (ax028/22/s, ax039/22/s) was triggered for this sporadic problem and will be reported separately if necessary.The incident described was not classified as a reportable adverse event after detailed investigation, because neither serious injury, death nor an unexpected, prolonged hospitalization of the patient or any other person occurred or could be expected.The corresponding probability according to the risk analysis is in the range of inconceivable.
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