Method and apparatus for analyzing material properties using reflected ultrasound

A method and apparatus which assesses the mechanical properties of a material by launching an ultrasound signal at the material while varying the angle of incidence and analyzing the amplitude of the ultrasound wave reflected by the material. The method and apparatus correlates extrema (maxima or minima inflection points) in the reflected angle with the angle of incidence of the transmitted signal to identify critical angles of incidence. The velocity of the pressure wave in the material has been found to be a function of a first critical angle corresponding to a first maxima as the angle of incidence is increased in the range 0.degree.-90.degree.. The velocity of the shear wave in the material has been found to be a function of a second critical angle corresponding to a second maxima following the first maxima. Young's modulus of elasticity, Poisson's modulus, and density can be approximated using the velocity of the pressure wave and shear wave for isotropic materials. A third critical angle corresponding to a minima after the first critical angle (reflected amplitude approaching o) has been found particularly useful in conjunction with the first and second critical angles in assessing bone density and in determining whether the second critical point is at a maximum or an inflection point. The extension of the method in which the plane of scattering is rotated around the normal to bone while keeping the point of observation fixed has been found particularly useful in assessing the mechanical properties of anisotropic materials such as cortical bone.Board of Regents, University of Texas Syste

Method and apparatus for analyzing material properties using ultrasound

Apparatus is disclosed for investigating the mechanical properties of a solid material such as bone, including means for positioning the apparatus in proximity to a surface of the material, at least one emitting ultrasound transducer, at least one receiving ultrasound transducer positioned to received ultrasound waves that have been emitted and have contacted the surface of the material, means for varying the angle of incidence of the emitted ultrasound wave towards the material, means for determining the alignment of the surface of the material with respect to the emitting and receiving ultrasound transdsucers, and signal analyzer means coupled to the receiving transducer for determining at least one characteristic of the received ultrasound wave which is indicative of a mechanical property of the material. A method is also disclosed of using such apparatus. The present invention permits the quick and efficient evaluation of treatment for osteoporosis, and whether that treatment has in fact reduced the tendency of a patient's bones to fracture.Board of Regents, University of Texas Syste