[en] In 2007, the European Commission (EC) commissioned a group of experts to undertake the revision of Report Radiation Protection (RP) 91, written in 1997, on 'Criteria for acceptability of radiological (including radiotherapy) and nuclear medicine installations' The revised draft report was submitted to the EC. Before publication, the EC issued this document for public consultation and has commissioned the same group of experts to consider the comments of the public consultation in further improving the revised report. The EC intends to publish the final report under its Radiation Report Series with the number RP 162. This paper introduces the project and presents the methodology adopted to devise the criteria of acceptability/suspension levels for nuclear medicine equipment. (authors)