A new method in diffraction tomography for medical image reconstruction
by Terence K.K. Chan
M.Phil. Electrical and electronic engineering
vi, 95 leaves : ill. ; 30 cm
An investigation of an improved method for ultrasound imaging is presented. The improved method is based on a type of diffraction tomography known as the Born approximation....[ Read more ]
An investigation of an improved method for ultrasound imaging is presented. The improved method is based on a type of diffraction tomography known as the Born approximation.
Specifically improvements of the Born approximation are performed by conveniently lumping all the image distortions produced by the Born approximation into a single function that is unknown a priori. We term this unknown function, the distortion function and our improvements are based on estimating it and then removing its distorting effects from the final image.
Three possible approaches of estimating the distortion function are provided, and we denote these as the zeroth, first and the modified first order extended Born approximations. The zeroth order approximation is a narrow band technique while the first order and the modified first order approximations are wide band.
Discussions on the implementation of the improved techniques are provided. Simulated results using the improved techniques are also presented. Results from nine circularly symmetric and four asymmetric objects are provided and comparisons to the conventional Born approximation is performed. The simulations indicate that dramatic improvements are possible.