Making operations on standard-library containers strongly exception safe

A failure detection circuit for a center metal grounded type X-ray tube. If the high voltage applying line for the anode side is kept opened and simultaneously for the cathode side is closed, the extraordinary cathode current may flow from the cathode through the center metal to the earth, which may cause a failure of the X-ray tube. In order to avoid such problem, there are provided the anode/cathode failure detectors which may interlock the operation of the X-ray radiation control circuit so as not to apply high voltages to the anode/cathode of the X-ray tube when failed in the high voltage apply lines.