CT Scan

CT Scan: Overview

Alternative Names: Computerized Axial Tomography Scan, CAT Scan, Computed Tomography Scan, Computerized Tomography

Computed Tomography (CT) is a more modern imaging tool that improves upon conventional X-rays by combining X-rays with computer technology that produces a more detailed, cross-section image of the body.  A CT scan shows the size, shape, and position of internal body structures, either as a cross-section or in 3D.

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Despite concerns over their safety, CT scans are generally less expensive and safer than the invasive procedures that they replace.  However, CT scans costs more and take more time than regular X-rays, and are not always available in rural facilities.

Why it is Recommended

A CT scan is particularly useful for detecting small structures inside the body, and for visualizing severe trauma to the brain, spine, chest, abdomen, etc.  Common uses include:

  • Allowing surgeons to prepare by seeing what they will find
  • Pinpointing tumors
  • Detecting bleeding in the brain, as well as aneurysms
  • Detecting brain tumors and brain damage
  • Locating and determining the size of tumors and abscesses throughout the body
  • Determining the type and extent of lung disease
  • Examining internal bleeding and organ trauma
  • Viewing spine or other bone injuries
  • Locating blood clots or blood vessel disease
  • Guiding biopsies

Due to the associated risks, doctors should not recommend CT scans without a good reason.

Instructions

The patient lies still on a table that slides into the CT scanner.  As the table moves, an X-ray emitter slowly rotates around the patient, taking multiple pictures from every direction.  These images are combined by a computer to produce a clear, two-dimensional cross-sectional view on a display screen.

As with a regular X-rays, barium sulfate or a dye may be given to the patient so that certain parts of the body show up more clearly.

Side-Effects; Counter-Indicators and Warnings

Giving up to 500 times the radiation dose of a single X-ray, much concern has been raised over the safety of computed tomography imaging.  Is the information gained from CT scans worth a small increase in cancer risk? The answer – in terms of early detection of serious problems and increased lifespan – is generally yes.  However, multiple CT scans should be avoided if at all possible.

A November, 2007 review in the New England Journal of Medicine determined that as many as one-third of all CT scans performed in the United States were unnecessary, which translates into a lot of unnecessary irradiation of patients.  Better communication between physicians, as well as informed patients, could avoid much of this.

Children are more at risk from radiation because have more years ahead of them and because their cells divide more rapidly, increasing chances of DNA damage.  A child's risk of developing a fatal cancer from a single CT scan has been determined to be as high as 1-in-500.

A CT scan is not generally recommended if you are pregnant, unless absolutely necessary.

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