The user of ionising radiation has prime responsibility for radiation protection within the context of its activities. The ASN ensures that it meets its obligations and assumes its responsibilities. In this respect, and as required by the IAEA standard described above, the ASN's supervision of users of ionising radiation involves examination of data, visits prior to commissioning of installations, inspections and finally discussion, in a climate of openness and cooperation, with the professional organisations (trade unions, orders, learned societies, etc.). This action directly concerns either the users of ionising radiation, or organisations approved to carry out technical inspections on these users.

These actions can be summarised as shown in the following table:

The purpose of the internal radiation protection checks is to regularly evaluate the radiological safety of installations that use ionising radiation sources, to check its level with respect to current regulations, and if necessary to reinforce it. Under application of the current regulations, internal radiation protection checks may be carried out as necessary by the person with competence for radiation protection (PCR), appointed and duly empowered by the head of the establishment, by approved supervisory bodies or by the IRSN. These internal checks do not replace the checks carried out directly by the ASN as part of its inspection activities at renewal or modification of an authorisation, or in the event of loss or theft of a source.

The table opposite specifies the various operators likely to be involved on the basis of the requirements of the Public Health and Labour Codes and decree 2001-1154 of 5 December 2001 concerning the obligation of maintenance and quality control for medical appliances as stipulated in article L. 5212-1 of the Public Health Code.