International survey in four European countries on diagnostic reference levels based on clinical indications in computed tomography.

objectiveTo collect and analyze radiation dose metrics from 23 commonly performed CT procedures, for which no national DRLs have yet been defined, as part of an international cooperation. The body region, the clinical task, and the relevant technical parameters were considered to define clinical diagnostic reference levels (DRLs). MATERIALS AND

methodsDuring 2022-2023, a multicenter study was performed in Austria, Germany, Italy, and Switzerland. Healthcare providers supplied processed data from their dose management systems. The 5%-level was used to assess the statistical significance of dose differences between the countries of participants, as well as age and manufacturer of the scanners.

resultsDose metrics from 87 CT systems in academic and non-academic, public and private healthcare facilities were analyzed. Dose values from the same body region but for different clinical tasks and/or using different techniques might differ significantly. For the same procedures, median dose values varied between systems by a factor of up to 39. Approximately a third of the surveyed systems showed doses within the DRLs suggested in this study, while 6% do not fulfill any DRL. No significant dose differences were observed between systems when comparing age, manufacturer or country.

conclusionsIn this international study, clinical DRLs were suggested for the first time for many different CT procedures, including dose-intensive procedures such as cerebral perfusion or the CT-guided interventional periradicular therapy. The diversity in protocol optimization is one of the main reasons for dose variations. Establishing the proposed DRLs can help harmonize exposure practice across country borders. CRITICAL RELEVANCE STATEMENT: In this international multicenter study, clinical task-based DRLs were suggested for 23 CT procedures to promote the optimization of the exposure practice, to reduce dose variations among institutions, even across national borders and to strengthen international cooperation among users. KEY POINTS: Analysis and differences in exposure practices in 23 different CT examinations in four neighboring European countries. Dose values for the same clinical tasks vary considerably between facilities using the same technology, but on average, not between countries. Establishing diagnostic reference levels helps to harmonize the exposure practice across country borders for frequently performed procedures.