Quantitative scanning acoustic microscopy investigation of cortical bone using a multilayer analysis method

An in vitro scanning acoustic microscopy measurement technique is described to assess the acoustical properties of human bone tissue at the level of individual lamellae. Contrast influences caused by defocus, surface edges and inclinations, respectively are separated or eliminated. The microscopic acoustic impedances of the remaining data points are determined by a dynamic calibration method. Cortical bone samples of the human femur embedded in polymethyl-methacrylate (PMMA) were investigated at a frequency of 900 MHz. The resulting impedance maps showed a strong structural dependence and the mean values were found to be in the range from 2 to 6 Mrayl, which is significantly lower than macroscopic bulk values of the bone compound measured by acoustic low frequency methods.