Ultrasonic radiation forces for elasticity imaging of 3-D tissue models

A novel ultrasonic elasticity imaging technique is being developed to study structural properties of hydropolymers including biological tissues. Radiation force is applied to harmonically stress the medium while ultrasonic Doppler and optical methods track deformation. This paper delineates basic system design and describes methods for pressure-field calibration using an acoustic radiometer, this extends to applying a radiation force to the media to remotely exert a locally oscillating stress field at the desired frequency within or on the medium surface. We use a single-element, spherically-focused, circular piston element driven by a pulsing voltage to produce a vibrating stress. Spectral Doppler techniques were successfully adapted to image the locally induced vibration. Our system delivers acoustic energy locally with an intensity matched to the acoustic attenuation and stiffness of the common biopolymers matrigel and chitosan.