Wavelet Transform Analysis of Ultrasonic Wave Propagation in Cancellous Bone

摘要

Ultrasonic waves targeted on cancellous bone separates into fast and slow waves according to the alignment of bone trabeculae. The characteristics of the specimen, however, can sometimes result in ambiguous wave separation. In this study, we proposed using wavelet transform as a new method of analyzing ultrasonic waveforms. Using continuous wavelet transform, two components were separated by fitting two-dimensional Gaussian function in scalogram. The relationship between bone volume fraction and the peak amplitude of the lower- and higher-frequency components showed a clear negative correlation; conversely, the relationship between bone volume fraction and the peak value ratio of the lower- and higher-frequency components showed a positive correlation. We recoginized lower-frequency component as the multiple reflections (forward scattering) in cancellous bone.