This work aims at establishing a set of diagnostic reference levels (DRLs) for various types of examinations performed in diagnostic and interventional radiology. The average doses for 257 types of radiological examinations were established during the 1998 nationwide survey on the exposure of the Swiss population by radiodiagnostics. They were calculated using appropriate dosimetric models and average technical parameters. The DRLs were derived from the average doses using a multiplying factor of 1.5. The DRLs obtained were rounded and compared to the data reported in the literature. The results are in most cases comparable to the DRLs determined by the 3rd-quartile method. These discrepancies registered in some cases, particularly for complex examinations, can be explained by signi®cant differences in the protocols and/or the technical parameters used. A set of DRLs is proposed for a large number of examinations to be used in Switzerland as temporary values until a national dosimetric database is set up.

Several recommendations for dose reduction are made. These include the re-evaluation of the patterns and justification for prescribing some particular types of dental examinations as well as the avoidance of unnecessary irradiation by the use of rectangular collimation and high sensitivity F-speed films.

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