Changes in distribution of bone densitometry equipment from 1996 to 2006 in Japan

Many types of bone densitometry equipment are available in Japan, but the numbers of such machines and the numbers of institutions that offer bone densitometry have not been clarified. We analyzed the data from annual surveys conducted by the Japan Osteoporosis Foundation from 1996 to 2006, and we obtained the following results on the use of densitometry equipment: (1) In 1996 there were 6,687 units of bone densitometry equipment in 6,483 institutions in Japan; in 2006 there were 16,371 units in 15,020 institutions. (2) In 2006, of the types of institutions with bone densitometry equipment, the number of clinics was the highest, followed in order by general hospitals, other types of institutions, screening institutions and university hospitals. Rates of increase in the installation of equipment in clinics and other types of institutions were high during the 11-year period from 1996. (3) From 1996 to 2006 the region of interest most frequently used for bone densitometry was the radius. However, during the 11-year period, the proportion of radial densitometry equipment in all institutions with bone densitometry equipment decreased, whereas the proportion of calcaneal densitometry equipment increased. (4) The number of dual-energy X-ray absorptiometry (DXA) units was the highest from 1996 to 2006. However, the proportion of DXA machines in all institutions with bone densitometry equipment decreased over the 11-year period, whereas the proportion of quantitative ultrasound (QUS) machines increased. (5) In 2006, bone densitometry equipment was available in 118 institutions per million Japanese people. Central DXA (spine/hip) equipment was available in 15 per million, radial DXA equipment in 63 per million, and calcaneal QUS equipment in 44 per million. (6) In 2006, among those places with bone densitometry equipment, 46% of university hospitals, 14% of general hospitals, 12% of screening institutions, 5% of clinics, and 6% of other types of institutions possessed more than one type of densitometry equipment. (7) In 2006, central DXA (spine/hip) was frequently available in university hospitals, radial densitometry equipment in general hospitals and clinics, and calcaneal densitometry equipment in screening institutions and other types of institutions.