Pediatric Nuclear Medicine
What is Pediatric Nuclear Medicine?
Nuclear medicine is a subspecialty within radiology that utilizes radioactive
substances to create images of body anatomy and function. The images are
developed based on the detection of energy emitted from the radioactive
substance given to the patient. Pediatric nuclear medicine refers to these
types of examinations in babies, young children and teenagers.
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What are some common uses of the procedure?
Pediatric nuclear medicine is used in the diagnostic workup of many childhood
disorders that are congenital (present at birth) or acquired later. It
helps in the evaluation of different organ systems including the kidneys,
liver, heart, lungs and bones. Examples of how nuclear medicine may be
used in children include the diagnosis of urinary blockage in the kidney;
infections and trauma in the bones; gastrointestinal bleeding; and various
tumors and their sites of spread in the body.
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How should my child be prepared for the procedure?
Most studies will involve an intravenous injection. Parents or legal guardians
are urged to speak with their child, depending on the child's age, before
the procedure and tell them they will be getting a "shot." For
infants and toddlers, if sedation is anticipated, such as for a bone scan,
instructions for your child regarding eating and drinking will be given
at the time the appointment is made. Also, reassure your child that you
will be able to be in the room with them during the procedure (except in
case of pregnancy).
If the procedure involves examination of the stomach, your child will have
to fast for a certain period of time before the test. If the procedure
involves examination of the kidneys, your child should drink plenty of
water before the test.
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What does the equipment look like?
During most nuclear medicine examinations, the child lies on a scanning
table. Consequently, the only piece of equipment usually noticeable to
the child is the specialized gamma camera used during the procedure. The
camera is enclosed in a metallic housing designed to facilitate imaging
of specific parts of the body. It can look like a large round metallic
apparatus suspended from a tall, moveable post, or a sleek one-piece metal
arm that hangs over the examination table. The camera can also be within
a large, doughnut-shaped scanner similar in appearance to a computed tomography
(CT) scanner. Often, this camera is beneath the table out of view.
A nearby computer console, usually in the same room, develops the images
from the data obtained by the camera.
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How does the procedure work?
The child is given a compound called a "radiopharmaceutical" or "tracer," usually
intravenously but sometimes orally. The tracer contains a small amount
of a radioactive substance that localizes in a specific body organ system.
The radiopharmaceutical to be used is determined by what part of the body
is under study. The amount given is determined according to the child's
body weight. Depending on the type of scan, it may take several seconds
to several days for the substance to travel through the body and accumulate
in the organs under study, thus a wide range in scanning times is possible.
The organs then give off energy as gamma rays. The gamma camera detects
the rays and works with a computer to develop an image of the specific
organs.
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How is the procedure performed?
The child is taken into the scanning room by a nuclear medicine technologist.
Next, the child is positioned on the scanning table. Then, a radiopharmaceutical
is administered by injection into a vein. Depending on which type of scan
is being performed, the imaging will be done either immediately or a few
hours or even two days after the injection. Scanning time varies, generally
from 20 to 45 minutes.
The gamma camera moves slowly along or around the child to obtain images
of the part of the body being examined. Sometimes sequential images are
obtained to show how an organ functions over time, for example, the kidneys.
Immediately after the procedure, a physician with specialized training in
nuclear medicine—a nuclear medicine physician—checks the quality
of the images to ensure that an optimal diagnostic study has been performed.
The same procedure will be followed if the radiopharmaceutical is given
orally.
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What will my child experience during the procedure?
Some discomfort during a nuclear medicine procedure may arise from the intravenous
injection, usually done with a small needle. With some exams, a catheter
may be placed into the bladder, which may cause some temporary discomfort.
Lying still on the examining table may be unpleasant for some patients.
Unfortunately, many children fear any visit to a medical center. This fear
is sometimes made worse when they see strange machinery and do not understand
how it works. Most healthcare personnel who deal extensively with children
know how to calm a child's fears. Many imaging suites have videotapes or
toys on hand to help a child pass the time. Often, a child can bring a
favorite toy to the examination room. Parents are encouraged to stay with
the child to help calm the child and decrease the child's motion during
imaging. Children less than three years old may be given a mild sedative,
usually orally, for longer exams if needed.
Unless the child has been sedated, daily activities can be resumed after
the nuclear medicine examination. The radiopharmaceutical loses its radioactivity
generally over 24 hours. It passes out of the body in the urine or stool.
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Who interprets the results and how do we get them?
Most children undergo a nuclear medicine examination because a referring
physician, often the primary care physician, has recommended it. The nuclear
medicine physician will interpret the images and forward a report to the
referring physician. It usually takes one to three days to interpret, report
and deliver the results.
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What are the benefits vs. risks?
- The functional information provided by nuclear medicine examinations
is unique and currently unattainable by using other imaging
procedures. For certain diseases, nuclear medicine studies yield the
most useful information needed to make a diagnosis.
- Pediatric nuclear medicine procedures will result in exposure of the
child to a small dose of radiation. However, the doses of radiopharmaceutical
administered are the smallest needed to perform the examination.
Nuclear medicine has been used in newborns and children for more than
three decades, and there are no known long-term adverse effects from
such low-dose studies.
- Allergic reactions to the radiopharmaceutical may occur, but are extremely
rare.
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What are the limitations of Pediatric Nuclear Medicine?
Nuclear medicine procedures are time-consuming. They involve administration
of a radiopharmaceutical, obtaining images, and interpreting the results.
It can take hours to days for the radiopharmaceutical to accumulate in
the part of the body under study. Imaging can take up to three hours to
perform. However, new gamma cameras have been introduced that can cut scanning
time in half.
Imaging infants and young children can be challenging because of crying
and motion. Doing a lengthy nuclear medicine procedure with a scared child
who is unable to hold still may be especially difficult for medical personnel.
Consequently, sedation is sometimes necessary.
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