[Computed X-ray densitometry].

Computed X-ray Densitometry (CXD) is a semi-automated method of radiographic densitometry. X-ray photographs of 2nd metacarpal bone, taken with a reference Aluminum phantom, are analyzed by a computed-densitometric machine (Bonalyzer). X-ray films are imaged by a CCD camera and displayed in a screen automatically. By pointing distal and proximal heads of the metacarpal bone, photodensity expressed as Aluminum concentration is computed. Parameters such as metacarpal cortical index (MCI) and cumulated photodensity (sigma Gs/D) at the mid-metacarpal bone are obtained. Precision determined by 5 photographs taken every 5 week, is 2%. Correlation with lumbar BMD assessed by DXA is 0.663 in elderly patients. Using this semi-automated method, radiographic densitometry can be used for clinical purpose, such as screening of patients with osteoporosis or observation of therapeutic effects. Especially, in patients over 70, this method has advantages, since lumbar BMD assessment with DXA at this age is hampered by degenerative diseases.