Date of Award
Master of Science
Electrical and Computer Engineering
Tomography refers to the cross-sectional imaging of an object from either transmission or reflection data collected by illuminating the object from many different directions. This technique revolutionized diagnostic medicine since it enabled doctors to view the slices of internal organs of the patient using x-rays. For the same reason, the method is being used in industry for applicationa such as inspection of turbine blades, rocket motors, ceramics, electronic components, castings, etc. The mathematical basis of CT was established by J.Radon in 1917 when he showed that it is possible to determine the value of a function over a region of space if the set of line integrals is known for all ray paths through the region. In the case of CT, the line integrals are derived from the x-ray intensities sensed by the detectors, and the function to be determined is the distribution of the x-ray attenuation coefficient over the object. However, the large number of calculations needed to accomplish the reconstruction ruled out any practical application to x-ray data until the availability of relatively rapid computers. Hounsfiled and Cornack first received a nobel prize in 1979 in medicine for their x-ray brain scanner with reconstruction time of 2 days. Since then several advances have been made resulting in fast reconstruction algorithms. Fourier weighted backprojection developed by Ramchandran and Laxminarayan is one of the most commonly used algorithm. This algorithm bring out the splendor and power of mathematical formulation of a problem. With very few assumptions, cross-sectional view of an object can be obtained with unprecedented accuracy. The amount of computation involved is still complex enough to demand considerable computing power.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu
Vivekanand R. Kini
Kini, Vivekanand R., "Tomographic inspection system using X-rays" (1994). Retrospective Theses and Dissertations. 237.