The acoustic properties of human femoral bone

Over the last decade, interest has grown in the use of the scanning acoustic microscope (SAM), with a single lens being used for both transmitting and receiving the acoustic signal. A major objective of this thesis was to determine if the transmission and ultrasonic techniques yield similar quantitative results, when measuring the elastic constants of human femoral bone. The transmission technique has been used since 1970 to yield values for the elastic properties of calcified tissue. Previously the SAM has been used as a qualitative tool, where an acoustic impedance map is produced. This map can show areas of bone remodelling and resorption at a microscopic level. Therefore, by proving that the SAM can give elastic constant data that corresponds to the values obtained from the transmission technique, a bone section can be directly scanned to give both quantitative and qualitative information. An experiment was conducted to obtain the acoustic impedance of individual quadrants from a human femur section by using the SAM. The acoustic impedance of bone was determined by calibrating the microscope with glass and plexiglass, two materials whose acoustic impedance has been widely documented. These results were compared to the stiffness results measured from the transmission technique, which has two transducers (one is a transmitter, and the other is a receiver). Finally, by retrieving accurate acoustic impedance maps from embedded specimens, there is great promise in the future for assuring the material properties of histological specimens embedded in polymethylmethacrylate