Thoracic CT (computer tomography) is an imaging method that uses x-rays to create cross-sectional pictures of the the chest and upper abdomen.
Chest CT; CT scan - lungs; CT scan - chest
How the test is performed
You will be asked to lie on a narrow table that slides into the center of the scanner.
Once you are inside the scanner, the machine's x-ray beam rotates around you. (Modern "spiral" scanners can perform the exam in one continuous motion.)
Small detectors inside the scanner measure the amount of x-rays that make it through the part of the body being studied. A computer takes this information and uses it to create several individual images, called slices. These images can be stored, viewed on a monitor, or printed on film. Three-dimensional models of organs can be created by stacking the individual slices together.
You must be still during the exam, because movement causes blurred images. You may be told to hold your breath for short periods of time.
Generally, complete scans take only a few minutes. The newest multidetector scanners can image your entire body, head to toe, in less than 30 seconds.
Certain CT exams require a special dye, called contrast, to be delivered into the body before the test starts. Contrast can highlight specific areas inside the body, which creates a clearer image. If your doctor requests a CT scan with contrast, you will be given it intravenously (by IV) through a vein in your arm or hand.
How to prepare for the test
Review Date: 08/13/2010
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.