Description
(4) Discussion and Conclusion
In this case, the wavelet decomposition alone does not suffice to optimize the signal processing and the incident wave reaching the object, also has to match the wavelets’ mathematical properties. We then propose a solution to achieve this goal, based on zone-by-zone simulated annealing algorithm. Then, we show through experimental results on geometrical mimicking human bone (without soft tissues), and on an ex vivo chicken drumstick (without skin), the usefulness of this WCE method.
(2) Material and Methods
Although this method is known to provide a potentially valuable means of imaging objects with similar acoustical impedance, in the case of bone imaging, difficulties are bound with the higher acoustical impedance difference, which strongly alters the propagation of the ultrasonic waves, and generally induces low Contrast-to-Noise Ratio (CNR). It is necessary to change the methods used for the acquisition and for the processing of the ultrasonic signals. More in particular, in order to obtain a better quantification while extracting characterization information from the received signal, we tried several approaches: filtering, spectrum analysis and the deconvolution of the signals.
(3) Results
Loosvelt and Lasaygues (2011) developed an alternative method based on a multi-scale decomposition procedure of the signals, enabling to process all the information available in terms of frequency and time. This method, called the "Wavelet-based Coded Excitation" (WCE) method, can be used to determine, independently, the velocity of the ultrasonic wave and the wave path across the thickness of parallelepiped plate. The aim of this new study is to investigate the feasibility of the WCE method as a mean of Contrast-to-Noise Ratio enhancement of bones imaging.
