[Photon densitometry in the diagnosis of osteoporosis]

The increased average life expectancy of the inhabitants of industrialised countries has led to a marked increase in degenerative pathologies, including osteoporosis. This has made it necessary to elaborate instrumental tests capable of identifying risk subjects in order to intervene as quickly as possible using appropriate prophylactic and therapeutic measures. Single and dual photon ray densitometry represents the first correct approach to quantitatively assess bone mineral content. It not only allows an early diagnosis to be made but also enables a longitudinal study to be made of patients receiving treatment. The main studies on the accuracy and precision of dual photon ray densitometry are reported together with the authors' findings regarding the definition of the fracture threshold and osteoporosis caused by metabolic and endocrinological disorders.