A regular check of the accuracy of X-ray inspection
systems by means of standard test pieces (STP) has
been established in the EU by the decision of the EU
Commission (2010) 774 and the European Civil
Aviation Conference (ECAC). Thus, all EU countries
and some non-EU countries are legally obliged to
regularly check and ensure the image quality and
performance of their X-ray inspection systems. For this
purpose, test kits contain samples of various materials
with different densities.