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The investigation of the reported event was performed by our experts.During an interventional procedure, the user reported that x-ray was unintentionally released.The analyzed log files showed that the reported incident was caused by an activated hand switch at table side.After the hand switch was pressed and the x-ray was active, the block radiation button was pressed a few times by the user.However, active radiation release is stopped by the emergency stop button not the block radiation button.The emergency stop button was not utilized by the user during the reported event.The patient skin dose was checked, and the exposure levels were limited within the acceptable range.The staff dosimetry reading did not detect any significant overexposure either.Siemens local service engineer went onsite and replaced the hand switch as well as the table side uli (user location interface) board proactively.The replaced parts were analyzed and did not show up any defects, which could explain the unintended x-ray release.With these results the exact root cause for the unintended x-ray could not be determined.In operator manual, it is stated that if unwanted radiation occurs, the radiation can be stopped at any time by pressing the red emergency stop button.There are various indications for the user that display radiation and a time limit of radiation in case of regular operation, unintended activation by system malfunction, and unintended activation by operator.Various measures addressing the risk of unintended radiation release are available as well: - limiting the dose exposure (dead man switch in flouro, maximal duration of acquisition scenes).- radiation indicator.- stopping radiation through emergency stop button.The occurrence rate of the aforementioned error pattern was checked.A possible error accumulation or even a systematic error, which leads to a corrective action of the installed base, could not be determined by the investigation.
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