Overview of Computed Tomography

The evolution of computed tomography (CT) as a viable medical tool will be considered from the time of the introduction of the original EMI CT Scanner, to the status of current and planned CT x-ray scanners. Changes in physical and engineering parameters, such as spatial resolution, noise levels, radiation dose, scan time, and reconstruction time, will be discussed. Limitations imposed by finite radiation dose on certain of these parameters will also be discussed. Differences between x-ray CT and conventional radiography will be illustrated by use of appropriate physical models and performance levels. A brief examination of the development of computed tomography in other medical diagnostic areas, such as nuclear medicine, ultrasound and heavy particle utilization, will be presented.