Indication-based diagnostic reference levels for adult CT-examinations in Finland.

A diagnostic reference level (DRL) is a predefined dose level, which should not be exceeded in an examination that is conducted appropriately on an average-sized patient. Since dose from only one examination should not be compared with a DRL, the average dose from a good sample of at least 10 average-sized patients should be compared. The previous DRLs for computed tomography (CT)-examinations for adults in Finland were issued in 2007 and only covered examinations conducted on a particular body region. Because the image quality requirements, and thus the dose needed, vary between different indications, there has been a call for indication-based DRLs for CT. The new indication-based DRLs for CT came into effect on June 2013. They are based on a dose survey performed in 2012. Doses were collected from examinations conducted on a particular body region, based on some indication and from some special examination types. The DRLs were set according to the third quartile approach. On average, the DRLs for a particular body region dropped ∼ 20 % from the previous DRLs.