Diagnostic radiology in Norway trends in examination frequency and collective effective dose.

The objective of the present work was to determine current levels and recent nationwide trends in radiological examination frequency, as well as to update corresponding collective effective dose estimates. Examination frequencies were obtained from radiology management systems at all hospitals and private radiology enterprises across Norway in terms of number of examination codes. During the last decade, the overall examination frequency increased by 16% to 910 per 1000 inhabitants, excluding nuclear imaging and dental radiology. The largest increase in examination frequency occurred in MRI (10-fold increase), followed by CT (more than doubling) and mammography (nearly 70% increase). The contribution to collective effective dose from radiological examinations was estimated to 4960 man Sv or 1.09 mSv per inhabitant; representing a 40% increase from 1993 to 2002. CT contribution to collective effective dose was estimated to account for 59% of the total as opposed to 30% in the previous survey.