The early detection of osteoporosis by Compton gamma ray spectroscopy.

The density of the distal end of the radius is one of the parameters used to determine the presence and degree of osteoporosis in patients. In this work the bone density has been determined by measuring the intensity of the Compton scattered photons, since this is proportional to the absolute density of the scatterer, in materials for which Z/A is constant. A collimated beam from a 500 mCi 137Cs source was used and the intensity of the scattered radiation measured at an angle of 90 degrees. The exact point of measurement was determined by a two-dimensional scanning technique. A plastic water phantom was used to calculate the correction needed for absorption and backscatter by the surrounding tissue. Bone density was measured by this method in 50 subjects. A good correlation was found between density of the radius and the degree of morphological change in the vertebrae. In a number of cases a low bone density was discovered without signs of osteoporosis in the spine. These findings were considered indicative of early osteoporotic change, not definable by routine X-ray techniques. This technique may be of value in the follow-up of patients and in controlling the effect of various treatment schedules.