Aperture diffraction theory applied to ultrasonic attenuation imaging

Abstract

Ultrasonic computed tomography (UCT) suffers significant quantitative errors when attempting attenuation imaging of refractive objects. The problem can be aggravated when a relatively large, single element, phase sensitive receiver is used. A method designed to maintain high resolution while minimizing refractive error is introduced. This technique (referred to as profile migration) utilizes an array receiver and an algorithm based on aperture diffraction theory. The profile migration and a more conventional migration approach are applied to data obtained from single projection scans of an object under refractive and nonrefractive conditions. Attenuation projections generated using 2 single-element receiver methods are also compared. Reconstructed images using projections produced via the profile migration method are compared to those using a technique currently employed on the UCT breast scanner. For both minimal and realistic refractive situations the profile migration method displays advantages over the other methods based on a qualitative assessment of the projections and images.