Cancellous and Cortical Bone Imaging by Reflected Tomography

Abstract

This paper deals with the inverse scattering problem observed when ultrasonic waves are used to analyze biological media. The objective is to image cancellous and cortical bone by ultrasonic reflected tomography (URT). Because strong contrast and high absorbance bodies such as bones cannot be imaged at usual ultrasonic high frequencies (>1 MHz), we adapted for low-frequency URT (< 1 MHz) our tomographic set-up and reconstruction and acquisition tools, previously developed for weakly scattered media. Indeed, when the frequency of the transducer decreases, the penetration length of the wave increases, which unfortunately makes resolution poor, inappropriate for bone imagery. To improve resolution, we extend the generalized inversion in the complementary bandwidth of the electro-acoustic set-up (Papoulis deconvolution). This resolution enhancement for human porous vertebrae and human and animal femur showed that high-resolution images can be obtained with low-frequency URT.