Numerical modeling techniques common to medical ultrasound and detection of undersea objects.

Abstract

Acoustic scattering from gallstones, diseased tissues, and objects on the ocean floor and submarines are all governed by the same underlying partial differential equations describing wave propagation in fluids and viscoelastic solids. These objects differ in size by many orders of magnitude. However, they are all the same “acoustic size” when each is insonified at a frequency such that the ratio of object-diameter-to-wavelength is the same for all. Objects of the same acoustic size have two important characteristics: (1) they exhibit qualitatively similar physical-acoustic phenomenology and (2) numerical modeling consumes similar computational resources. Given these observations, many of the numerical modeling techniques developed by the U.S. Navy for acoustic scattering from undersea objects may be applicable to biomedical ultrasound applications. This paper explores these possibilities. NSWC PCD has developed a computer simulation system for modeling the acoustic color (target strength versus frequency and aspect angle) of realistic objects. It automatically runs hundreds of thousands of three dimensional FE models, changing the mesh and finite fluid boundaries of the models as they sweep over frequency and yielding uniform accuracy with frequency. This paper will present an overview of the technology and numerical verification and validation of the system. [Work supported by ONR and SERDP.]