What Is a Chest CT Scan?
A chest computed tomography (to-MOG-ra-fee), or CT,
scan is a painless, noninvasive test. It creates precise images of the
structures in your chest, such as your lungs. “Noninvasive” means
that no surgery is done and no instruments are inserted into your body.
A chest CT scan is a type of x ray. However, a CT
scan’s pictures show more details than pictures from a standard
Like other x-ray tests, chest CT scans use a form of
energy called ionizing radiation. This energy helps create pictures of the
inside of your chest.
Doctors use chest CT scans to:
- Show the size, shape, and position of your lungs
and other structures in your chest.
- Follow up on abnormalities that are found on
standard chest x rays.
- Find the cause of lung symptoms, such as
shortness of breath or chest pain.
- See whether you have a lung problem, such as a
tumor, excess fluid around the lungs, or a
pulmonary embolism (PULL-mun-ary EM-bo-lizm; a blood clot in the lungs).
The test also is used to check for other conditions, such as tuberculosis
(tu-ber-kyu-LO-sis), emphysema (em-fi-SE-ma), and
The chest CT scanning machine takes many pictures,
called slices, of the lungs and the inside of the chest. A computer processes
these pictures; they can be viewed on a monitor or printed on film. The
computer also can stack the pictures to create a very detailed,
three-dimensional (3D) model of organs.
Sometimes, a special substance (called contrast dye)
is injected into a vein in your arm. This substance highlights areas in your
chest, which helps create clearer images.
Chest CT scans have few risks. Because the test uses
radiation, there may be a slight risk of cancer.
Children are more sensitive to radiation than adults
because they’re smaller and still growing.
The amount of radiation will vary with the type of
CT scan. On average, though, the radiation will not exceed the amount a person
is naturally exposed to over 3 years. The benefits of a CT scan should always
be weighed against the possible risks.
Rarely, people have allergic reactions to the
contrast dye that’s sometimes used for chest CT scans. If this happens,
your doctor will give you medicine to relieve the symptoms.