Three-Dimensional Ultrasound C-Scan Imaging Using Holographic Reconstruction

Abstract

A three-dimensional ultrasound C-scan imaging method based on holographic reconstruction has been developed. Using wide angle coherent illumination of the object and holographic principles, high lateral resolution is achieved throughout the imaging space. For this method the object is insonified by monochromatic ultrasound bursts, and the wavefronts reflected from the different object levels are recorded into a stack of holograms, each of which corresponds to a different object level. After recording each plane of the three-dimen- sional hologram is first Fourier transformed. Then each plane wave spectrum is transferred to the object space by a transfer function, and the wavefront of the object plane is calculated using an inverse Fourier transform. Finally all the object planes are combined to form a three- dimensional image, which is displayed as front, side, and top projec- tions and as a stereopair. Both simulated and real measurements of test objects that contained point-like features were accomplished. An ultrasonic frequency of 4 MHz was used in all measurements. The sim- ulated measurements showed that the resolution of the three-dimen- sional imaging method is better than 2 mm in all three directions. Using effective coding methods and fast Fourier transform algorithms, the imaging time of a 64 X 64 X 32-point image could be reduced to 2 h with an ordinary 256-kword minicomputer.