Contrast resolution enhancement of Ultrasonic Computed Tomography using a wavelet-based method – Preliminary results in bone imaging

• Lasaygues Philippe
• Guillermin Régine
• Metwally Khaled
• Fernandez Samantha
• Balasse Laure
• Petit Philippe
• Baron Cécile

• Ultrasonic tomography
• Resolution
• Coded-excitation
• Wavelet
• Bone

Ultrasonic Computed Tomography (USCT) is a biological tissue imaging modality. USCT is mainly efficient in improving image resolution by eliminating noise and interferences. The strong variations in acoustic properties between soft tissues and bone generate complex signals consisting of several packets with different signatures. USCT contrast ratio is degraded. In this paper, a method to enhance USCT resolution is investigated. The method, called the "Wavelet-based Coded Excitation" (WCE) method, is based on the wavelet decomposition of the signal and on a suitable transmitted incident wave correlated with the experimental setup , mathematically expressed using an extended form of simulated annealing. The goal of this study is to investigate the feasibility of the WCE method to enhance the Contrast-to-Noise Ratio of USCT for bone objects. Experiments are conducted with a bone phantom, and with a chicken drumstick, using a circular antenna equipped with 1MHz-transducers. Results demonstrate the capabilities and limitations of the method.