Standards Development

Scope

This European standard specifies a method for the measurement of effective focal spot dimensions above 0,1 µm of X-ray systems by means of the edge method applied to digital images taken from hole type or disk type gauges. The imaging quality and the resolution of X-ray images depend highly on the characteristics of the effective focal spot, in particular the size and the two-dimensional intensity distribution as seen from the detector plane.

This document provides instructions for determining the effective size (dimensions) of standard, mini and micro focal spots of industrial X-ray tubes for users in applications where the pin hole method of EN12543-2 is not practicable. This determination is based on the measurement of a profile of an image of a hole or disk type gauge. The method as described in this document can be used for long term monitoring of focal spot sizes without a pin hole camera. The accuracy of this method is lower than the one of EN12543-2, EN 12543-5, using ASTM hole plate IQIs (ASTM E 1025, E 1742), due to its manufacturer tolerance of ±10%.

Purpose

The revision is needed regarding the state of the art. The document shall be revised and harmonized with the Annex of ASTM E 1165- 2020 as user method. In order to cover the full range of effective focal spot sizes, three different methods are described in EN 12543- 2: 2021, EN 12543-4: 1999, EN 12543-5: 1999, which are actively used. The recently revised pin hole method EN 12543-2 is intended for effective focal spot dimensions above 0,1 mm of X-ray systems up to and including 1000 kV tube voltage with digital detectors and evaluation procedures. The edge measurement method of EN 12543-5: 1999 is intended for measurement of effective focal spot sizes between 5µm and 300µm and mainly applicable for the use with microfocus tubes. The edge method of EN 12543-4: 1999 is intended for effective focal spot size monitoring of macrofocus tubes only, by users with spot sizes of s > 0,5 mm and up to 500 kV. The EN 12543-4: 1999 describes films as detector only and is outdated. The standard needs to be extended by the application of Digital Detectors and digital evaluation procedures. Currently, it is observed that EN 12543-4 is not applied by users anymore. ASTM E 1165- 20 contains an Annex, which permits the application of spot size measurements for users by simple technical means and concepts, similar to the old EN 12543-4 using digital detectors and simple numeric procedures. The revision shall adapt the procedure of the Annex of ASTM E 1165 for users permitting the monitoring of spot sizes. Additionally, new hole targets shall be described, which will extend the application range down to spot sizes < 1 µm (nano focus tubes).