Rays theory for experimental characterisation of acoustical and dimensional properties of bone diaphysis

Abstract

Ultrasound, bone, diaphysis,International audienceThe aim of this study is to establish an instrumental approach allowing dimensional and acoustical characterization of the cortical thickness and of the medullar marrow constituting the bone diaphysis. This one is modeled by a hollow cylinder. The solution of the direct problem, which is required before the evaluation of the searched parameters, is done using the Theory of Rays. The parameters are evaluated from the delay phase of reflected and transmitted waves in the tube. The precision of the theoretical estimation of arrival times of echoes is then experimentally verified. The solution of the inverse problem is next approached and validated on test objects made of Plexiglas and Duraluminium as well as in vitro on bovine samples. The whole results are very satisfactory. The acoustical velocities reported are in keeping with reference data and the dimensional parameters evaluated follow the internal and external outlines of the bone diaphysis in a satisfactory way