Diffusion of digital radiology modalities in the Nordic countries and Japan.

The Nordic countries have 23 million inhabitants. About 14 million radiology examinations are performed annually at hospitals and in primary health care. This represents about 600 examinations per 1000 inhabitants per year. Japan, on the other hand, has 125 million inhabitants and annually performs about 200 million radiology examinations at hospitals and in primary health care. This represents about 1600 examinations per 1000 inhabitants per year. The above figures do not include dental X-ray examinations. Between 15% and 20% of all radiology examinations in the Nordic countries and about 5% in Japan are performed with digital modalities such as computerized tomography, digital subtraction angiography, computed radiography, and magnetic resonance imaging. Computerized tomography is the most diffused digital X-ray modality in the Nordic countries with 95,000 inhabitants per scanner while Japan only has 17,000 inhabitants per scanner. For magnetic resonance imaging the difference is almost of the same order. Japan has the same diffusion of magnetic resonance imaging units per 100,000 inhabitants as the Nordic countries have of computerized tomography scanners. The large difference between Japan and the Nordic countries regarding diffusion of digital radiology modalities is explained mainly by differences in the nature and organization of radiology services.