Ashley S Shaw, Addenbrooke's Hospital, Cambridge, UK
Adrian K Dixon, University of Cambridge, Cambridge, UK
Published online: February 2010
Computed tomography (CT) comprises an X‐ray tube and a bank of detectors that rotate around a patient, taking multiple exposures
from different angles. The data from the detectors, essentially a density map of the body, is reconstructed to form an image
which may be manipulated to any plane. The development of CT during the 1970s heralded the start of sophisticated cross‐sectional
imaging. Such cross‐sectional images have, in turn, revolutionized the diagnostic investigation for many clinical conditions
and demand for imaging grows inexorably; in 2006, an estimated 62 million CT studies were performed in the United States alone,
almost five times the number in 1990. Increasingly, the radiation dose involved in CT has become a major issue and, alongside
high‐speed imaging, is the focus of current developments.
The first CT machine was built in the early 1970s by Sir Godfrey Hounsfield.
CT comprises an X‐ray tube and a bank of detectors rotating around a patient to produce a dataset from which an image can
Current technology enables rapid acquisition (<10 s) of submillimetre resolution images.
The contrast adjacent structures may be enhanced by the administration of oral, intravascular or rectal contrast medium.
CT images may be displayed in any plane and manipulated in a number of ways depending on the clinical indication.
There are innumerable indications for CT across many clinical specialties, with many other investigations becoming obsolete.
CT exposes patients to a relatively high dose of radiation; efforts should be made to ensure that the investigation is necessary
and that the technique employed uses the lowest dose possible while answering the clinical problem.
Dual‐energy CT enables one to determine the chemical composition of structures in addition to their morphology.
There is currently extensive research in the use of CT perfusion imaging, adding functional information to the anatomical
CT machines are often combined with nuclear medicine machines to give hybrid functional and anatomical information.
Keywords: computed tomography; CT; clinical applications; development; radiation; X‐ray
Brenner DJ and
Computed tomography: an increasing source of radiation exposure.
New England Journal of Medicine
Representation of a function by its line integrals, with some radiological applications.
Journal of Applied Physics
75 years of radon transform.
Journal of Computer Assisted Tomography
Caoili EM and
Multi‐detector CT urography: a one‐stop renal and urinary tract imaging modality.
George A and
Cardiac computed tomography: current practice and future applications.
Reviews in Cardiovascular Medicine
Hart D and
Radiation Exposure of the UK Population from Medical and Dental X‐ray Examinations.
Didcot: National Radiation Protection Board.
Hillman BJ and
The American College of radiology imaging network: clinical trials of diagnostic imaging and image‐guided treatment.
Seminars in Oncology
Computerized transverse axial scanning (tomography): part 1. Description of system.
British Journal of Radiology
Schaller S and
Advanced single‐slice rebinning in cone‐beam spiral CT.
Klotz E and
Spiral volumetric CT with single‐breath‐hold technique, continuous transport and continuous scanner rotation.
Hayball MP and
Colour perfusion imaging.
Computed tomographic tomography: current perspectives and future directions.
van Rossum AB,
Ton ER et al.
Pulmonary embolism: validation of spiral CT angiography in 149 patients.
Taguchi K and
Algorithm for reconstruction in multi‐slice helical CT.
Schaefer‐Prokop C and
van der Molen A
Spiral and multislice computed tomography of the body.
Sahani DV and
Advances in MDCT.
Radiologic Clinics of North America