Abstract

Images reconstructed using a limited number of projections measured over a narrow angle range are characterized by elliptic distortions along the directions of the raws used, and poor contrast at angles not used (anisotropic resolution). Thus, for example, a reconstruction computed using a few views measured about the vertical would have a vertical ellipsoidal distortion and poor resolution along the horizontal. We are interested in this particular case in connection with our experiments to achieve computed tomography from a few radiographs acquired at different angles using an ordinary overhead or mammographic x-ray unit. The aim is to transmit these images over telephone lines to provide inexpensive computed tomography to people living in remote areas. The angular coverage is restricted to the range 55-125 degrees. We are also attempting to compute high resolution tomographic images of the breast from a few film mammograms. Similar cases arise in industrial non-destructive testing and electron microscopy of biological macromolecules.

© 1983 Optical Society of America