Non-linear ultrasonic tomography of high-contrasted materials

Régine Guillermin (1) , Philippe Lasaygues (1)

1 LMA - Laboratoire de Mécanique et d'Acoustique [Marseille]

This study focuses on the ultrasonic characterization and imaging of elastic materials like cylinders or tubes. In this case, ultrasonic wave propagation is greatly perturbed by the difference in the acoustic impedance between the scatterer and the surrounding medium (soft tissues, water or coupling gel), which results in considerable parasite events such as the refraction, attenuation and scattering of the waves. The aim of this work is then to solve a non-linear inverse scattering problem. Analytical or algebraic approaches may be applied generally involving in a "classical" problem of minimization of the differences between modeling data and measurements. Several strategies can be used to model the forward problem and to solve the inverse problem simply, efficiently and accurately. The distorted diffraction tomography is an inversion iterative method and belongs to the class of algebraic reconstruction algorithms. This method was developed to increase the order of application of the Born approximation (in the case of weakly contrasted media) to higher orders. The iterations are performed numerically by solving the forward and inverse problems at every iteration after calculating an appropriate Green's function; the previous iteration serves in each case to define the surrounding medium with a variable background. This yields quantitative information about the scatterer, such as the speed of sound and the attenuation. Quantitative ultrasonic imaging techniques of this kind are of great potential value in fields such as medicine, underwater acoustics and non-destructive testing.

Domaines: Acoustique [physics.class-ph]; Acoustique [physics.class-ph]

Régine Guillermin, Philippe Lasaygues. Non-linear ultrasonic tomography of high-contrasted materials. International Congress on Ultrasonics, 2007, Vienne, Austria. CD-ROM(4 p.). ⟨hal-00440741⟩