Thoracic CT is a computed tomography scan of the chest and upper abdomen.

You will be asked to lie on a narrow table (gantry) that slides into the center of the scanner. Depending on what is being scanned, you may lie on the stomach, back, or side. If contrast media (dye) is to be given, an IV (intravenous needle or tube) will be placed in a small vein of your hand or arm.

As with standard photography, if you move while the CT image is being taken, it will blur. Because of this, the operator of the scanner will tell you when to hold your breath and not move.

As the exam takes place, the gantry will advance small intervals through the scanner. Modern spiral scanners can perform the examination in one continuous motion of the gantry. Generally, complete scans will only take a few minutes. However, additional contrast-enhanced or higher-resolution scans will add to the scan time. The newest multi-detector scanners can image the entire body, head-to-toe, in under 30 seconds.

The health care provider may advise you to avoid eating or drinking for 4 - 6 hours prior to the scan, if contrast dye is to be used.

The CT scanner has a weight limit to prevent damage to the mechanized gantry. Have the health care provider contact the scanner operator if you weigh more than 300 pounds.

Metal interferes with the x-rays, so you may be asked to remove jewelry and wear a hospital gown during the study.

The x-rays are painless. The primary discomfort may be from the need to lie still on the table.

If intravenous contrast dye is given, you may feel a slight burning sensation in the injected arm, a metallic taste in the mouth, and a warm flushing of the body. These sensations are normal and usually go away within a few seconds.