ISO 32543-3:2026

This document specifies a method for the measurement of focal spot sizes within the range of 5µm to 300µm of X-ray systems up to and including 225kV tube voltage. This determination is based on the evaluation of an image with a dedicated focal spot that has been radiographically recorded using an edge and evaluated with a digital method.

The imaging quality and the resolution of X-ray images depend highly on the characteristics of the effective focal spot, in particular its size and the two-dimensional intensity distribution as seen from the detector plane.

For the characterization of commercial X-ray tube types (i.e. for advertising or trade), the nominal values of AnnexA are preferred.

NOTE The same procedure can be used at higher kilovoltages by agreement but the accuracy of the measurement can be poorer.