CT Scan (General)
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CT Scan (General)

(Computed Tomography Scan; Computed Axial Tomography; CAT Scan)

En Español (Spanish Version)


A computed tomography (CT) scan uses x-ray technology to take multiple cross-sectional views of the inside of the body. A CT scan can take clearer pictures of organs, bone, soft tissue, blood vessels, and areas of the body not seen on regular x-rays. IAs a result, it can be more accurate than other imaging studies in diagnosing certain problems.

CT Scan of the Head

Breast self-exam, step 5

© 2008 Nucleus Medical Art, Inc.

Parts of the Body Involved

This depends on the medical problem and the part of your body being studied.

Reasons for Procedure

Some of the primary uses for CT scanning include:

  • Studying the chest and abdomen
  • Diagnosing cancer
  • Determining the size and location of a tumor
  • Diagnosing and treating skeletal problems
  • Diagnosing and treating vascular diseases
  • Planning radiation treatments for cancer
  • Guiding biopsies and other procedures
  • Planning surgery
  • Measuring bone mineral density and diagnosing osteoporosis
  • Identifying injuries to internal injuries

A CT scan is not recommended if you are pregnant.

Risk Factors for Complications During the Procedure

  • Allergies, if you are given a contrasting agent during the procedure
  • Kidney problems, if you are given a contrasting agent during the procedure

Talk to your doctor if you are pregnant, since the procedure may affect your pregnancy.

What to Expect

Prior to Procedure

  • Physical exam and medical history
  • Pregnancy test
  • Determine if you have any allergies
  • Prescribe a mild sedative, if you have anxiety or a fear of enclosed spaces

Do not eat solid food during the four hours before your appointment.

  • If your doctor prescribes a sedative:
    • Arrange to have someone drive you to and from the procedure, and for help at home after your procedure.
    • Do not eat or drink at least four hours before the exam.
    • Take your sedative before the exam as directed by your doctor.
  • You will be asked to remove any metal objects, such as jewelry, hairpins, hearing aids, glasses, wigs, and/or nonpermanent dentures.
  • You may be asked to drink a contrast agent (eg, barium), which can help your radiologist interpret your scans.


None, unless you receive a mild sedative for anxiety or fear of enclosed spaces

Description of the Procedure

You will lie (usually on your back) on a movable bed that slides into the donut-shaped CT scanner. Depending on the type of scan you are receiving, an intravenous line may be placed in your hand or arm. A saline solution and contrasting agent may be injected during the exam.

The technologist will leave the room and give you any necessary directions via an intercom. The machine will take a series of pictures of the area of your body that is being studied. Your bed may move slightly between pictures.

After Procedure

You will be asked to wait until the CT staff is sure all the necessary information has been collected.

How Long Will It Take?

The procedure takes about 10-15 minutes.

Will It Hurt?

There is no pain reported with a CT scan.

Possible Complications

  • Allergic reaction to contrast material, if it is ingested or injected
  • Renal failure from intravenous contrast
  • Risks of sedation, if a sedative is used
  • Risks of radiation exposure, including a risk to your fetus if you are pregnant

Average Hospital Stay

You will be able to go home after the CT scan.

Postoperative Care

  • If you took a sedative, do not drive, operate machinery, or make important decisions until the sedative wears off completely.
  • If you are breastfeeding and received a contrast dye during your scan, wait at least 24 hours after the exam before breastfeeding again, unless told otherwise by your doctor.


The CT images will be sent to a radiologist who will analyze them and report the results back to you and/or your primary physician.

Call Your Doctor If Any of the Following Occurs

  • Symptoms of allergic reaction (eg, hives , itching, nausea, swollen or itchy eyes, tight throat, difficulty breathing)
  • Worsening of your symptoms


Center for Devices and Radiological Health

Radiological Society of North America


Canadian Association of Radiologists

Canadian Radiation Protection Association


Computed tomography (CT)—body. Radiological Society of North America website. Available at: http://www.radiologyinfo.org/en/info.cfm?pg=bodyct&bhcp=1 . Accessed May 29, 2007.

CT scan: a guide for patients. Department of Radiology, Brigham and Women’s Hospital website. Available at: http://brighamrad.harvard.edu/patients/education/ct/ctguide.html#q2 . Accessed May 29, 2007.

Last reviewed April 2008 by Jill Landis, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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