CT (Computed Tomography) Scan
What is a CT scan (computed tomography)?In conventional x-rays, a beam of energy is aimed at the body
part being studied. A plate behind the body part captures the variations
of the energy beam after it passes through skin, bone, muscle, and other
tissue. While much information can be obtained from a regular x-ray,
specific detail about internal organs and other structures is not
available.
With computed tomography scan (also called CT or CAT scan), the x-ray
beam moves in a circle around the body. This allows for many different
views of the same organ or structure, and provides much greater detail.
The x-ray information is sent to a computer which interprets the x-ray
data and displays it in two-dimensional form on a monitor.
CT scans may be done with or without contrast. "Contrast" refers to a
substance taken by mouth or injected into an intravenous (IV) line that
causes the particular organ or tissue being studied to be seen more
clearly.
What is the preparation for a CT scan?If your child's physician schedules a CT scan of the heart or
chest and decides to use contrast dye, your child may need to be NPO
(fasting, nothing by mouth) for four hours prior to the procedure. You
will receive instructions about this from your child's physician or
another healthcare professional.
You will need to let your child's physician know if your child has ever
had a reaction to any contrast dye, or if he/she is allergic to iodine or
seafood. If your teenage daughter is pregnant or could be pregnant, you
should notify the physician prior to the procedure.
Children may receive a mild sedative before the procedure to make them
feel more comfortable, and to help them to remain still and quiet during
the procedure, which may last 30 to 60 minutes.
Parents may be able to stay with their child in the CT scan room until
he/she becomes sleepy, but are usually asked to wait in another area
during the procedure to avoid exposure to unnecessary radiation.
How is the CT scan performed?The CT scanner is located in a large room. Your child will lie
on a narrow table that slides into the hollow tube-shaped scanner.
Your child may have an intravenous (IV) line for contrast medication.
The contrast medication may be injected prior to the procedure or during
the procedure.
The CT physician and staff will be in an adjacent room where the
equipment controls are located. However, they will be able to see your
child through a large window and will be monitoring him/her constantly
during the procedure. If your child is not sedated, he/she will be given a
call bell device to let the staff know if he/she needs anything during the
procedure. Speakers are located inside the scanner so that your child can
hear instructions from the CT staff and they can hear your child respond.
Once the procedure begins, your child will need to remain very still at
all times so that movement will not adversely affect the quality of the
images. At intervals, he/she will be instructed to hold his/her breath, if
possible, for a few seconds. He/she will then be told when to breathe.
Your child should not have to hold his/her breath for longer than a few
seconds, so this should not be uncomfortable. Young children who cannot
hold still for the procedure will be given medication to help them relax
or sleep during the CT scan.
If the CT scan is being done "with and without contrast," your child
will receive contrast medication through an IV about halfway through the
procedure. He/she may feel warm or flushed just after the dye goes into
the vein - this is a normal feeling and it will go away shortly.
Once the procedure is finished, the table will slide out of the
scanner. If your child received medication for relaxation or sleep, he/she
will be monitored until the medication wears off and he/she is awake
again. If an IV was inserted, it will be taken out after the procedure is
over and your child is awake.
You may be asked to wait for a short time while the radiologist reviews
the scans to make sure they are clear and complete. If the scans are not
sufficient to obtain adequate information, additional scanning may be
done.
The test normally takes approximately 30 to 60 minutes.
What happens after the procedure?Without sedation, your child should be able to resume normal
activities immediately, unless your child's physician instructs you
otherwise.
With sedation, your child may feel groggy, tired, or sleepy for a
period of several hours after the procedure. However, the sedation effects
should disappear within a day or so.
Depending on the results of the CT scan, additional tests or procedures
may be scheduled, to gather further diagnostic information.
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