Computed Tomography Scan of the Chest

In chest CT scan, a body scanner delivers x-rays to the chest region at many different angles. A computer then compiles this information to construct highly detailed, cross-sectional images of the chest cavity.

In some cases, a contrast dye may be injected to better define tissues and organs on the images. This procedure is very useful for detecting abnormalities in the chest region that cannot be found with conventional x-rays.

Purpose of the Chest CT Scan

  • To obtain an image of the lungs and other chest structures that is more accurate than a routine chest x-ray
  • To determine the precise anatomy of chest structures prior to surgery.
  • To identify bleeding or fluid collections in the lungs or other regions of the chest
  • To evaluate injury to the blood vessels in the chest, the lungs, ribs and spine
  • To determine the cause of cough, shortness of breath, chest pain or fever
  • To detect and evaluate tumors in the chest, including those that form in the chest and those that have spread there from other parts of the body
  • To determine if tumors in the chest are responding to treatment
  • To develop a plan for radiation therapy
  • To detect and evaluate lung disorders, such as lung cancer, old or new pneumonia, tuberculosis, emphysema, chronic obstructive lung disease (COPD), bronchiectasis, inflammation or other diseases of the pleura (membrane that enfolds the lungs; e.g., pleurisy), diffuse interstitial lung disease and congenital abnormalities

Who Performs Chest CT Scan

Special Concerns about Chest CT Scan

  • CT scans are not usually done during pregnancy because exposure to ionizing radiation may harm the fetus.
  • People who experience claustrophobia may find it difficult to undergo a CT scan, which takes place in a narrow, tunnel-like structure.
  • This test may not be possible for severely overweight individuals (over 300 lbs).
  • People with allergies to iodine or shellfish may experience an allergic reaction to the iodine-based contrast material.

Before the Chest CT Scan

  • Inform your doctor if you have an allergy to iodine or shellfish. You may be given a combined antihistamine-steroid preparation to reduce the risk of an allergic reaction.
  • Tell your doctor if you suffer from claustrophobia. He or she may prescribe a sedative that can help you tolerate the procedure.
  • You may be asked to fast for 4 to 6 hours before the procedure if a contrast dye is to be used or if sedation is likely to be necessary.
  • Wear loose-fitting clothing. You may be asked to wear a hospital gown.
  • Remove any metal objects, including watches, hair clips, eyeglasses, dentures and jewelry, hearing aids and removable dental work.
  • If a contrast dye is to be administered, an intravenous (IV) needle or catheter is inserted into a vein in your arm immediately before the test begins.
  • Tell your doctor about recent illnesses or other medical conditions, and if you have a history of chronic conditions such as heart disease, asthma, diabetes, kidney disease or thyroid problems.
  • Tell your doctor if you are pregnant or may be pregnant.

What You Experience during Chest CT Scan

  • You are asked to lie on your back on a narrow table that is then advanced into the CT scanner.
  • The scanner, which encircles you, takes pictures at different intervals and varying levels over your chest area, so you will feel the table move during the test. The resulting images are displayed on a viewing monitor and recorded on x-ray film.
  • You must remain still because any movement can distort the image on the scan.
  • The examiner may advise you on how to control your breathing at several points during the procedure.
  • A contrast dye may be administered through the IV line in your arm to help define blood vessels and various tissues.
  • The test may take 30 to 45 minutes. However, if a contrast dye is used, the procedure time may be doubled.

Risks and Complications of Chest CT Scan

  • CT scans involve exposure to low levels of radiation.
  • Some people may experience an allergic reaction to the iodine-based contrast dye, which can cause symptoms such as nausea, sneezing, vomiting, hives, and occasionally a life-threatening response called anaphylactic shock. Emergency medications and equipment are kept readily available.

After the Chest CT Scan

  • If contrast dye was used, blood may collect and clot under the skin (hematoma) at the injection site; this is harmless and will resolve on its own. For a large hematoma that causes swelling and discomfort, apply ice initially; after 24 hours, use warm, moist compresses to help dissolve the clotted blood.
  • You are encouraged to drink clear fluids to avoid dehydration and help flush the contrast dye out of your system.
  • Delayed allergic reactions to the contrast dye, such as hives, rash, or itching, may appear 2 to 6 hours after the procedure. If this occurs, your doctor will prescribe antihistamines or steroids to ease your discomfort.

Chest CT Scan Results

  • The doctor will examine the CT scans for evidence of any abnormality.
  • If a definitive diagnosis can be made, appropriate treatment will be initiated, depending on the specific problem.
  • In some cases, additional tests, such as a chest MRI or bronchoscopy, may be needed to establish a diagnosis and determine the extent of the problem.


The Johns Hopkins Consumer Guide to Medical Tests

Simeon Margolis, M.D., Ph.D., Medical Editor

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at

Published: 04 Jan 2012

Last Modified: 19 Mar 2015