Analysis of Current Practice of CT Examinations

Background: The number of CT examinations performed in Denmark increased from 14,500 examinations in 1979 to 301,617 in 2005. This implies increased radiation dose to the population. On this background, an analysis of the practice for CT examinations including potential limitations of radiation exposure and the associated risk is needed.

Purposes: To analyse 1) the current use of CT in a university department compared to 1996, 2) the radiation dose and risk associated with the examinations and 3) the use of CT in Denmark since 1979.

Material And Methods: The administrative data of CT examinations performed in the Department of Radiology, Aarhus Sygehus, during 2005 and 1996, respectively, were obtained. Additionally national CT data were obtained from the database at the National Board of Health.

Results: In 1996 1,840 patients obtained 5,538 CT examinations at Aarhus Sygehus. Their mean age was 46.7 years (0-88). The most frequent referring speciality was oncology followed by abdominal surgery and orthopaedic surgery. In 2005 3,769 patients obtained 11,216 CT examinations. They were generally older with a mean age of 56.9 years (0-97). The most frequent referring speciality was oncology followed by chest medicine and abdominal surgery. In 2005 the total effective dose was 71,043 mSv (mean 18.9 mSv/per patient). According to the BEIR VII model this radiation level corresponded to a risk for inducing a cancer in 7 patients, being fatal in half of them. The national data showed a gradual increase of the number of CT examinations from 1979 to 2005, most pronounced after year 2000 coinciding with the introduction of multi-slice CT (MSCT).

Conclusion: The number of CT examinations at Aarhus Sygehus doubled during a 9 year period. The increase occured especially in middle and high age groups.