The estimation of bone mineral content at selected skeletal sites by γ-ray absorption

Abstract
γ-ray absorption has been used to measure mineral contents at five sites in human long bones excised from 38 male and 25 female cadavera. The sites were in the central and distal portions of the right femur and right radius, and in the central portion of the right 3rd metacarpal. The absorption measurements were made using radiation from 125I and 241Am sources. Calibrations to provide bone mineral content at each site were obtained by comparing these measurements with the weights of ash residues of bone sections taken from the sites. Inter-relationships between mineral contents, measured by γ-ray absorption, at the different sites have been established for males and females. These relationships have been examined for their value in estimating bone mineral at one site from determinations at other sites. Confidence limits (P > 0·95) for the error in estimating mineral content at mid radius from measurements at each of the other sites, expressed as percentages of the directly measured values, varied from ±20 per cent to ±33 per cent in males and from ±20 per cent to ±24 per cent in females. When the means of each set of four values predicted from the other sites were compared with the measured values, the confidence limits were ±25 per cent and ±16 per cent in males and females respectively.