CT Scan - Computed Axial Tomography

What is Computed Axial Tomography ("CT" or "CAT" scan)?

A "CT" or "CAT" scan is a way of looking inside your body with a special camera. The images produced are cross-sectional, like slices in a loaf of bread. During a CT exam at the Ogden Clinic, the scanner takes multiple cross-sectional images of you. The images are created with the help of a computer and can depict various internal body parts in greater detail than standard X-ray films. This greatly enhances the doctor's ability to diagnose a medical condition.

Common uses of this procedure:

In cancer detection, computed axial tomography is used to scan for abnormal masses which might be malignant tumors (cancers). A CT scan can show the size and shape of a tumor, its precise location in the body, and whether it's solid or hollow. Although a CT scan sometimes is able to tell the difference between a benign (noncancerous) or malignant (cancerous) tumor, the final diagnosis is made by a biopsy or other test.

When a needle biopsy is performed for cancer diagnosis, CT scanning also can be used to guide the insertion of the biopsy needle into precisely the right location for sampling a tumor.

In addition to cancer detection, a CT scan has many other uses for Ogden Clinic patients, including the detection of abscesses, strokes, head injuries, and bleeding inside the skull.

In obese patients, CT scanning may be more useful than ultrasound, since large amounts of body fat can interfere with ultrasound waves.

How does it work?

The CT scanner contains a large donut-shaped ring that your body slowly passes through on a moveable table. As you pass through the ring, the scanner takes a complete 360- degree picture of you and sends it to a computer. Then the mechanical table moves a small distance - less than half-an-inch - positioning you for the next picture. These pictures are reconstructed by the computer to form a complete image of your internal anatomy.

To make a clearer picture of certain parts of your body, some CT scans require the use of contrast materials, which are substances showing up as pure white on the X-ray. The two types of contrast materials used are barium, which you drink, and iodine, which is injected by means of an IV (intravenous) line.

Patient Comfort

The test itself is completely painless. You will be asked to lie quietly on the CT scanner's "patient couch" during the study. Depending on the type of study being done, you may be injected with or asked to drink contrast material.

Because contrast agents contain iodine, which causes an allergic reaction in some individuals, be sure to tell the technologist, nurse or radiologist if you have had an allergic reaction to these agents before, or if you have any other allergies. You may have been given contrast material earlier as part of a CT scan, a kidney x-ray (also called an IVP), or a heart or blood vessel catheterization (also called an angiogram).

At Ogden Clinic we use nonionic contrast exclusively, which poses less risk to patients.

Preparation Required

You will be asked to change into a gown for most procedures. Metal objects can affect the image, so avoid clothing with zippers and snaps. You may be asked to remove hairpins, jewelry, eyeglasses, hearing aids and any removable dental work that could obscure the images. You also may be asked to refrain from eating or drinking anything for 3 hours before the exam. Women should always inform their doctor or X-Ray technologist if there is any possibility that they are pregnant.