Archives of Acoustics, 25, 4, pp. , 2000

Adaptation of image reconstruction algorithm for purposes of ultrasound transmission tomography (UTT)

A. B. Dobrucki
Wrocław University of Technology, Institute of Telecommunication and Acoustics

K. J. Opieliński
Wrocław University of Technology, Institute of Telecommunication and Acoustics

In this research, the convolution and backprojection method
has been adapted for the purposes of image reconstruction in ultrasound
transmission tomography (UTT). In particular, a complete computer algorithm
enabling the use of different convolving and interpolation functions has been
developed. A technique of reducing and scaling the tomographic measuring data to
minimize the reconstruction errors is proposed. The convolution and
backprojection method was optimized through a choice of a versatile convolving
function and a simple interpolation function, and it was tested using simulated
and actual tomographic measuring data. After reconstruction, good-quality images
were obtained. It has been found that the number of measuring rays determines
the resolution of an image, the accuracy with which the size of structures is
imaged and the accuracy with which the image point values are reconstructed,
whereas the number of measuring projections determines the dynamics and
distortion of an image. Because of computation time and image blur, an optimum
reconstruction grid size, according to the visualization quality criterion,
should be chosen. The convolution and backprojection algorithm optimized in this
research can be applied directly to the UTT visualization of the internal
structure of objects as a distribution of local sound velocities in this
structure, reconstructed on the basis of measurements of mean times of the
passage of an ultrasonic wave through a cross-section of an object immersed in
water, in a parallel ray projection geometry.
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