Osteoporosis, a loss of bone mineral content accompanying certain diseases, endocrine disorders, and inactivity, is a relatively common medical problem which is difficult to detect in its early stages. Over the past few years, considerable interest has developed in procedures which promise to provide quantitative data concerning changes in bone mineral content during the development of a particular disorder or during the course of therapy for the disorder. These procedures have involved primarily densitometric measurements of radiographs of the extremities (Ref. 1, 2, 3) and use of a Nal(T1) detector to detect monoenergetic photons transmitted through the extremities. (Ref. 5, 6, 7, 8, 9) In general, the latter method, usually described as photon absorptiometric analysis, has provided measurements of highest accuracy and greatest reproducibility over extended periods of time. Also, photon absorptiometric measurements usually require orders of magnitude less exposure of the patient to radiation.