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 Imaging
tests
What
types of imaging tests are used for children?
X-rays
During an x-ray, electromagnetic
waves (a form of light) pass through the body and create an image on film.
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Time:
Each x-ray takes only a few seconds, like a picture taken with a camera.
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Radiation:
X-rays expose the body to very small amounts of radiation, but only to the
areas of the body being studied.
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Pain:
None.
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Before
the test: Nothing special needs to be done before the test.
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During
the test: The body part to be examined is placed between the x-ray machine
and the x-ray film. Other parts of the body may be covered with a lead-lined
apron to reduce radiation exposure. The machine is turned on, and a picture
is taken. Patients must keep very still for the image to be clear. Young
children may need special straps to keep them still during the test.
Fluoroscopy
Fluoroscopy is a type
of x-ray that creates a real-time "x-ray movie" of the inside of
the body. An x-ray beam placed on a specific area of the body creates images
that are shown on a TV-like monitor.
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Time:
About 5 to 20 minutes.
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Radiation:
Higher than x-rays, but it depends on how long the test lasts.
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Pain:
None, but preparing before the test may be unpleasant.
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Before
the test: For some types of fluoroscopy tests patients may need to fast,
drink only liquids, or have an enema. Sometimes a contrast material (a fluid
that shows things in the body that are hard to see without it) is injected
or given by mouth. If the child cannot drink it, a tube may need to be placed
through the mouth to the stomach.
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During
the test: The room is darkened, and the area of the body being examined
is placed between the x-ray and fluoroscopy screen. Images of the body are
then sent to a monitor where they can be seen in motion.
Computed tomography
or CT scan
A CT scan is a special
type of x-ray that uses computers to create detailed images of the body.
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Time:
A CT scan only takes a few seconds.
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Radiation:
Higher than x-rays but lower than the dose from fluoroscopy.
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Pain:
None, unless the child will need an injection of a contrast material. This
must be done through a vein (IV) in the arm.
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Before
the test: A contrast material may need to be injected or taken by mouth.
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During
the test: The patient lies on a narrow table that slides in and out
of the CT scanner. The x-ray tube rotates around the patient, sending information
to a computer that forms the images.
Magnetic resonance
imaging (MR imaging or MRI)
An MRI uses a large and
powerful magnet, radio waves, and a computer to create very detailed images
of the inside of the body.
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Time:
About 30 to 60 minutes.
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Radiation:
None.
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Pain:
None, but patients may need an injection of a contrast material and an IV.
Also, some patients may feel cramped in the machine (open MRI machines are
available in some areas). During scanning, loud humming and knocking will
be heard. Small children may be frightened by these noises.
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Before
the test: Younger children may need to be sedated before the test.
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During
the test: The patient lies on a table that slides into the scanner (a
narrow tunnel that holds the magnet). Inside the scanner, the patient will
hear a fan and feel air blowing. Because the machine can be noisy, patients
are given earphones. Some centers have headphones that your child can use
to listen to music during the exam.
Ultrasound (sonography)
Ultrasound uses sound
waves to create images of the body. The sound waves enter the body, and the
returning echoes are captured as images.
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Time:
15 minutes to 1 hour.
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Radiation:
None.
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Pain:
None.
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Before
the test: In some cases, patients may need to fast or drink more water
before the test.
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During
the test: First, a special jelly or oil is put on the skin. Next, a
hand-held device called a transducer is moved back and forth over the area
being examined. The transducer creates sound waves (that can't be heard
or felt) that are reflected back to the machine. A computer creates images
from the sound waves.
Nuclear imaging
A nuclear imaging scan
(sometimes called radionuclide scanning) shows the structure of a body part
as well as how it works. Before the scan, a radioactive substance called a
tracer is injected or given by mouth. A machine called a gamma camera used
outside the body then detects the rays of energy given off by the tracer,
and an image is created and shown on a computer screen.
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Time:
Between 15 minutes and 1 hour.
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Radiation:
Less radiation than from fluoroscopy or CT. The tracer loses its radioactivity
within 24 hours, leaving the body in the urine or stool.
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Pain:
None, but patients may need the tracer injected and an IV.
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Before
the test: The tracer is usually given by mouth or through an injection.
Patients may need to fast or drink a lot of water before some nuclear imaging
scans.
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During
the test: After the tracer is in place, the patient lies on a scanning
table. The camera is then moved slowly over the body. Images are created
and displayed on a computer.
Published online: 3/07
Source: Imaging Tests: A Look Inside Your Child's Body (Copyright ©
2006 American Academy of Pediatrics)
Parents can find more information
on this topic in Caring for Your Baby and Young Child: Birth to Age 5.
To order a copy of this book visit the AAP
Bookstore.
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The information contained
in this publication should not be used as a substitute for the medical care
and advice of your pediatrician. There may be variations in treatment that your
pediatrician may recommend based on individual facts and circumstances.
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