Modeling and Analysis of Ultrasonic Echoes Reflected from a Surface under Two Layers

Fat and muscle layers in the human soft-tissue causes degradation of resolution and distortions of shape in ultrasound images of organs. Novel ultrasonic applications such as registration between CT and ultrasound images, requiring comparable levels of accuracies between modalities could suffer from the distortions in ultrasound images. In this work, we describe a possible method to compensate or correct for these distortions in ultrasound images. This can be used as a pre-processing step before registration with other modalities. We derived a model of ultrasound field after reflection from an interface embedded in two layers. Experiments were performed using single-element transducers and custom made tissue mimicking phantoms of fat and muscle and a steel-block. We fit the model to the experimental data using Levenberg-Marquardt inversion.