This European standard specifies a method for the measurement of focal spot dimensions within the range of 5 µm
to 300 µm of X-ray systems up to and including 225 kV tube voltage, by means of radiographs of sharp edges.
The image quality and the resolution of X-ray images highly depend on the characteristics of the focal spot. The
imaging qualities of the focal spot are based on the two dimensional intensity distribution in the object plane.
For certification purposes the radiographic technique is used.
NOTE The same procedure can be used at higher kilovoltages by agreement but the accuracy of the measurement
may be poorer.