Prog Med Phys.  2021 Mar;32(1):1-17. 10.14316/pmp.2021.32.1.1.

Basic Physical Principles and Clinical Applications of Computed Tomography

  • 1Development Headquarter, FutureChem Co., Ltd, Korean Institute of Radiological & Medical Sciences (KIRAMS), Seoul, Korea
  • 2Division of Applied RI, Korean Institute of Radiological & Medical Sciences (KIRAMS), Seoul, Korea


The evolution of X-ray computed tomography (CT) has been based on the discovery of X-rays, the inception of the Radon transform, and the development of X-ray digital data acquisition systems and computer technology. Unlike conventional X-ray imaging (general radiography), CT reconstructs cross-sectional anatomical images of the internal structures according to X-ray attenuation coefficients (approximate tissue density) for almost every region in the body. This article reviews the essential physical principles and technical aspects of the CT scanner, including several notable evolutions in CT technology that resulted in the emergence of helical, multidetector, cone beam, portable, dual-energy, and phase-contrast CT, in integrated imaging modalities, such as positronemission-tomography一CT and single-photon-emission-computed-tomography一CT, and in clinical applications, including image acquisition parameters, CT angiography, image adjustment, versatile image visualizations, volumetric/surface rendering on a computer workstation, radiation treatment planning, and target localization in radiotherapy. The understanding of CT characteristics will provide more effective and accurate patient care in the fields of diagnostics and radiotherapy, and can lead to the improvement of image quality and the optimization of exposure doses.


Computed tomography; Physical principle; Clinical application; Technical aspects; Radiation dose
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