A chest CAT scan is a painless test that uses a special X-ray machine to take black-and-white
pictures of a patient's lungs, heart, blood vessels, airway passages, ribs and lymph
The doughnut-shaped machine circles your child's body, taking pictures to provide
cross-sections of internal organs from various angles. These pictures are sent to
a computer that records the images. It can also put them together to form a three-dimensional
(3-D) image. A radiology technician does the CAT scan (also called a CT scan or a
computed axial tomography scan).
Why It's Done
A chest CAT scan can detect signs of inflammation, infection, injury or disease
of the lungs, breathing passages (bronchi), heart, major blood vessels, lymph nodes,
and esophagus. A doctor may order a chest CAT scan to identify illnesses related to
the lungs and breathing passages, to diagnose birth defects, view a tumor, evaluate
blood vessels that feed the heart and lungs, or evaluate the effects of a traumatic
Your child may be asked to remove all clothing and accessories and change into
a hospital gown because buttons, zippers, clasps, or jewelry might interfere with
Your child may have to avoid eating and drinking for a few hours before the scan
so the stomach will be empty. Fasting is required if your child needs to be sedated
or will receive a contrast solution, which highlights certain parts of the body so
doctors can see more detail in specific areas.
If your daughter is pregnant, it's important to tell her technician or doctor because
there's a small chance that the radiation from the CAT scan may harm the developing
baby. But if the CAT scan is necessary, precautions can be taken to protect the baby.
Procedure times vary, from several minutes to 45 minutes. This timing depends on
the age of the child, whether contrast solution is given, and whether sedation is
needed. The actual exposure time to radiation is much less.
Your child will enter a special room and lie down on a narrow table. A chest CAT
scan is performed with your child lying on his or her back, stomach, or side. If contrast
solution is required, it may be given through an IV that will be placed in your child's
hand or arm. Placing the IV will feel like a quick pinprick, but the solution is painless
as it goes into the vein. Or your child may be given oral contrast, which is a special
fluid to drink before the procedure. Some kids don't like the taste, but it can be
flavored to make it more appealing.
The technician will position your child, then step behind a wall or into an adjoining
room to operate the machine, viewing your child through a window. The technician will
speak to your child through an intercom. You'll be able to stay in the CAT scan room
until the test begins, then you'll join the technician in the outer room or you might
be asked to sit in a waiting room. If you stay with the technician, you'll be asked
to wear a lead apron to protect certain parts of your body.
Sedation may be required if your child can't lie still for the scan, which is common
among infants and young kids. Sedation medicines are given through an IV line and
help to keep your child comfortable during the CAT scan. When the procedure begins,
the table moves through the CAT machine. Older kids will be asked to hold their breath
and stay still for a few seconds at a time to prevent the images from being blurred.
What to Expect
Your child won't feel anything as the CAT scan is taken, but may hear whirring
and buzzing as the machine works. The room may feel cool due to air conditioning used
to maintain the equipment. Some kids may feel uncomfortable lying still for extended
After the scan is complete, your child will be asked to wait a few minutes so the
technician can review the quality of the images. If they are blurred, some parts of
the CAT scan may need to be redone. If your child required sedation, it will take
a little while for the medicine to wear off.
Getting the Results
The CAT scan images will be looked at by a radiologist (a doctor who is specially
trained in reading and interpreting X-ray images). The radiologist will send a report
to your child's doctor, who will discuss the results with you and explain what they
Results are usually ready in 1-2 days. If the CAT scan was done on an emergency
basis, the results can be made available quickly. In most cases, results can't be
given directly to the patient or family at the time of the test.
In general, CAT scans are very safe, although more radiation is required than in
a regular X-ray. Any exposure to radiation poses some risk to the body, but the amount
used in an individual CAT scan procedure isn't considered dangerous. It's important
to know that radiologists use the minimum amount of radiation required to get the
If your daughter is pregnant, there's a risk of harm to the developing baby, so
precautions must be taken. Contrast solutions are generally safe, with a very low
incidence of allergic reactions. They may contain iodine, which might cause problems
for kids with an iodine or shellfish allergy, and other illnesses. Make sure to tell
your doctor about any medication, dye, and food allergies that your child may have.
Some patients who are at risk for allergic reaction to the contrast solution may need
medications like antihistamines or steroids to minimize the risk of adverse reaction.
If your child needs sedation, there's a slight chance of slowed breathing due to
the medications. If there are any problems with the sedation, the CAT scan staff is
prepared to treat them right away.
Helping Your Child
You can help your child prepare for a CAT scan by explaining the test in simple
terms before the procedure. You can describe the room and the equipment that will
be used, and reassure your child that you'll be nearby. For older kids, be sure to
explain the importance of staying still so the scan can be completed quickly and parts
of it don't have to be repeated.
If You Have Questions
If you have questions about why the chest CAT scan is needed, speak with the doctor.
You can also talk to the CAT scan technician before the procedure.