A computed tomography (CT) scan uses
X-rays to make detailed pictures of structures inside
of the body.
During the test, you will lie on a table that is
attached to the CT scanner, which is a large doughnut-shaped machine. The CT
scanner sends X-rays through the body area being studied. Each rotation of the
scanner provides a picture of a thin slice of the
organ or area. All of the pictures are saved as a
group on a computer. They also can be printed.
In some cases, a
dye called contrast material may be used. It may be put in a vein (IV) in your
arm, or it may be placed into other parts of your body (such as the
rectum or a joint) to see those areas better. For some
types of CT scans you drink the dye. The dye makes structures and organs easier to see on the CT
A CT scan can be used to study all parts of your
body, such as the chest, belly, pelvis, or an arm or leg. It can take pictures
of body organs, such as the liver,
adrenal glands, lungs, and heart. It also can study
blood vessels, bones, and the spinal cord.
is a special test that is not widely available. It uses a steady beam of X-rays
to look at movement within the body. It allows the doctor to see your organs
move or to guide a
biopsy needle or other instrument into the right place
inside your body.
Why It Is Done
CT scans are used to study areas of
the body and the arms or legs.
- Chest (thorax). A CT scan of the chest can look for
problems with the lungs, heart,
esophagus, the major blood vessel (aorta), or the tissues in the center of the chest.
Some common chest problems a CT scan may find include infection,
lung cancer, a
pulmonary embolism, and an
aneurysm. It also can be used to see if cancer has
spread into the chest from another area of the body.
- Abdomen. A CT scan of the abdomen can find
abscesses, infection, tumors, an aneurysm, enlarged
lymph nodes, foreign objects, bleeding in the belly,
inflammatory bowel disease, and
- Urinary tract. A CT scan of the kidneys,
ureters, and bladder is called a CT KUB or CT urogram.
This type of scan can find
kidney stones, bladder stones, or blockage of the
urinary tract. See a picture of a
CT of diseased kidneys . A special type of CT scan, called a CT intravenous
pyelogram (IVP), uses injected dye (contrast material) to look for kidney stones, blockage, growths, infection, or
other diseases of the urinary tract.
- Liver. A CT scan can find liver tumors, bleeding
from the liver, and liver diseases. A CT scan of the liver can help determine
the cause of
- Pancreas. A CT scan can find a tumor in the
pancreas or inflammation of the pancreas (pancreatitis).
- Gallbladder and bile ducts. A CT scan can be used
to check for blockage of the
Gallstones occasionally show up on a CT scan. But
other tests, such as
ultrasound, usually are used to find problems with the
gallbladder and bile ducts.
- Adrenal glands. A CT scan can find tumors or
enlarged adrenal glands.
- Spleen. A CT scan can be used to check for an
injury to the
spleen or the size of the spleen.
- Pelvis. A CT scan can look for problems of organs
in the pelvis. For a woman, these include the
fallopian tubes. For a man, the pelvic organs include
prostate gland and the
- Arm or leg. A CT scan can look for problems of the
arms or legs, including the shoulder, elbow, wrist, hand, hip, knee, ankle, or
Other uses for a CT scan
CT scan may be used to make sure a procedure is done correctly. For example,
the doctor may use CT to guide a needle during a tissue biopsy or to guide the
proper placement of a needle to drain an
For people with cancer, a CT
scan can help determine how much the cancer has spread. This is called staging