Comparison of Fast and Slow Wave Correlation with Various Porosities between Two Measurement Technique

Abstract

With the discovery of fast and slow wave propagated through cancellous bone, the precision of the ultrasound measurement using through transmission technique to estimate bone quality getting better but limited to the certain part of the skeletal site. Thus, the pulse echo technique is proposed to solve the problem as the technique only uses one transducer to operate. The objective of this paper is to conduct an experiment for through transmission and pulse echo technique to investigate correlation fast and slow wave with various porosity of polyurethane foam. The recorded “incident” and “reflected” waves (mix wave) is then processed with the bandlimited deconvolution method in order to estimate the overlapping fast and slow wave. Further, the parameters for the mix, fast and slow waves for both incident and reflected wave are calculated, plotted against porosity and compared based on the correlation coefficient performance. The result shows that, the slope of attenuation of reflected and incident for both fast and slow waves shows a good correlation with porosity. The effect of scattering playing an important role for the total attenuation instead of absorption at high porosity, due to the acoustic properties of polyurethane foam is almost the same with water. Compared to mix wave, fast and slow wave is more correlated to the changes of porosity. Moreover, the reflected wave may suffer more effect of attenuation compared to the incident wave, thus, makes the correlation between wave parameter with porosity is lesser. Overall result indicates that, analyzed fast and slow wave instead of mix wave to estimate bone quality might improve the measurement accuracy.