Set Of Projection Angles Research Articles

A scanning and sampling scheme for computationally efficient algorithms of computer tomography

A scanning and sampling scheme for computerized tomography that reduces the number of required interpolations in the reconstruction algorithm is presented. Hence, the computational load associated with interpolation is also reduced. For the case in which no restriction are placed on the sampling rates of the scanner, a set of projection angles along with their corresponding sampling rates are derived such that no interpolation is required to calculate the final image points for the display grid. From this result a reduced interpolation scheme is developed for the case when upper and lower bounds exist on the sampling rates. The choice of an optimal set of projection that will maintain an image quality comparable to a sampling scheme of regular measurement geometry, while minimizing the computational load is discussed. The Cartesian-grid scanning and sampling (CGSS) scheme developed is compared to a sampling scheme of regular measurement geometry through a computer simulation. The results demonstrate that for higher sampling rates and images of limited pixel dimension, the CGSS scheme can reduce the computational load of the reconstruction process and maintain comparable image quality. >

Book reviewLecture Notes in Biomathematics. Questions of uniqueness and resolution in reconstruction from projections. By KatzMyron B., pp. ix + 175, 1978 (Springer-Verlag, Berlin/Heidelberg/New York), DM 21.50, $11.80. ISBN 3–540–09087–8

These notes provide a readable account of a mathematical exploration into the uniqueness of reconstructions obtained from projection data. It is shown how a particular set of projection angles is the least demanding on the resolution of the data, and that providing this set is used the limitation on the resolution of the reconstruction, which is necessitated by the requirement for a unique solution, may be demonstrated. Its is shown how to deal effectively with noisy data and to choose the optimum projection angles under practical working conditions. A chapter on improving the EMI head scanner provides a practical application of the theory.