Abstract
Previous experimental studies indicate that backscatter coefficient for human calcaneal trabecular bone varies approximately as frequency cubed. This frequency dependence has been shown to be consistent with a model in which trabeculae are thought of as long thin cylinders composed of a substance with the same material properties as hydroxyapatite. The true material properties of human trabecular bone are not known however. Based on reported measurements of material properties of many bones and bone-like substances, it is possible that the density and longitudinal sound speed of trabecular bone material are far lower than the hydroxyapatite model would suggest. In this letter, it is shown that the frequency dependence of backscatter is still expected to be approximately cubic for wide ranges for density and longitudinal sound speed (encompassing the conceivable ranges for trabecular bone).