Computed Tomography

ALTERNATIVE NAMES:

Computed tomography (CT); TAC; TC

DEFINITION:
It is an imaging method that uses x-rays to create cross-sectional images of the body.

HOW DO THE TEST?

The patient is asked to lie down on a narrow table that slides into the center of the scanner. Depending on the study being performed, it may be necessary for the patient to lie on your back, stomach or side.
Once inside the scanner, the X-ray beam of the machine rotates around the person. (Modern scanners "spiral" can perform the exam in one continuous motion).
Small detectors inside the scanner measure the amount of X-rays passing through the body part 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. You can create three-dimensional models of organs stacking the individual slices.
You must lie still during the exam, because movement causes blurred images. Also, you may be asked 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, from head to toe, in less than 30 seconds.

WHAT ARE THE RISKS?

CT scans and other x-rays are monitored and regulated to ensure minimal use of radiation. CT scans do create low levels of ionizing radiation, which has the potential to cause cancer and other defects. However, the risk associated with any individual scan is small, but increases as carried out numerous additional studies.
In some cases, you can still make a TC if the benefits outweigh the risks. For example, it can be more risky not to have the exam, especially if your doctor thinks you might have cancer.
Generally are not recommended for pregnant women abdominal CT because it may harm the fetus. Women who are or may be pregnant should talk with their doctor to determine if ultrasound can be used instead.
The medium most commonly used intravenous contrast contains iodine. A person allergic to iodine may experience nausea, sneezing, vomiting, itching or hives. If the person you definitely must be given such contrast, your doctor may choose to treat you with antihistamines (such as Benadryl) or steroids before the test. The kidneys help filter the iodine out of the body, so those people with kidney disease or diabetes should receive plenty of fluids after the test and close monitoring of renal function. If the person suffers from diabetes or are on kidney dialysis, talk to your doctor about the risks before the test.
The contrast medium rarely cause anaphylaxis (a life-threatening allergic reaction). However, if the person has any difficulty breathing during the test, you should notify the scanner operator immediately. Scanners come with an intercom and speakers, so the operator can hear the person at all times.