Nuclear medicine is a radiology subspecialty encompassing a number of
studies in which a small dose of radioactive material is administered to
a patient, allowed to disperse through the body, and then imaged with a
special camera that detects the radiation emitted from the body. These
types of studies produce images of body anatomy and function that cannot
be obtained by other methods.
How Does the Procedure Work?
You are given a small dose of radioactive material, usually
intravenously but sometimes orally, that localizes in specific parts of
the body. This compound (called a radiopharmaceutical or tracer) gives
off energy as gamma rays. The radiopharmaceutical that is used is
determined by what part of the body is being studied since some
compounds collect in specific organs better than others. Depending on
the type of scan, it may take several seconds or several days for the
substance to travel through the body and accumulate in the organ under
During the examination, you will lie down on a scanning table where a
specialized nuclear imaging camera will be used to perform the
procedure. Depending on what is being scanned, this camera may be a
large, round, metallic apparatus suspended from a moveable post or a
metal arm that hanging over the table. The camera may also be within a
large, doughnut-shaped structure similar to a CT scanner or beneath the
table out of view.
The gamma camera detects and captures the energy emitted by the
radiopharmaceutical. Imaging time varies, generally ranging from 20 to
45 minutes. A nearby computer console processes the data from the
procedure to produce images and measurements of organs and tissues.
After the procedure, a radiologist with specialized training in nuclear
medicine checks the quality of the images to ensure that an optimal
diagnostic study has been performed.
Is Nuclear Medicine Safe?
Nuclear medicine procedures result in exposure to very small doses of
radiation. Generally, radiation to the patient is similar to that
resulting from standard x-ray examinations. Nuclear medicine has been
used for more than five decades, and there are no known long-term
adverse effects from such low-dose studies. However, pregnant women and
breast-feeding mothers must be carefully screened to determine which
studies are safe for them. (In general, exposure to radiation during
pregnancy should be kept to a minimum).
The radioactive agents used in these procedures are carefully handled
and measured. The dosages involved are extremely low and are completely
safe, though pregnant women and breast-feeding mothers must be carefully
screened to determine which studies are safe for them. Most of the
radioactivity passes out of your body in urine or stool. The rest simply
disappears through natural loss of radioactivity over time.
Some minor discomfort during a nuclear medicine procedure may arise from
the intravenous injection, usually done with a small needle. Allergic
reactions to the radiopharmaceutical material are extremely rare. With
some special studies, a catheter may be placed into the bladder, which
may cause temporary discomfort. As well, lying still on the examining
table for long periods may be uncomfortable for some patients.
Applications for Nuclear Medicine
Nuclear medicine images can assist the physician in diagnosing many
diseases and conditions:
Analyze kidney and spleen function
Image blood flow and function of the heart
Scan lungs for respiratory and blood-flow problems
Identify blockages of the gallbladder
Evaluate bones for fracture, infection, arthritis or tumor
Determine the presence or spread of cancer
Identify bleeding into the bowel
Locate the presence of infection
Measure thyroid function to detect an overactive or underactive
Detect tumors, infection and other disorders by evaluating organ
How Should I Prepare for the Procedure?
Usually, no special preparation is needed for a nuclear medicine
examination. However, if the procedure involves evaluation of the
stomach, you may have to skip the meal immediately before the test. If
the procedure involves evaluation of the kidneys, you may need to drink
plenty of water before the test.
Benefits of Nuclear Medicine
The information provided is unique and currently unattainable by using
other imaging procedures.
For many diseases, nuclear medicine studies yield the most useful
information needed to make a diagnosis and to determine appropriate
treatment, if any.
Nuclear medicine is much less traumatic than exploratory surgery.
Limitations of Nuclear Medicine
Nuclear medicine procedures can be time-consuming. Preparing and
administering the radiopharmaceutical requires time and it can take
hours or days for the radiopharmaceutical to accumulate in the part of
the body under study. While the procedure is being performed, patients
must remain as still as possible to ensure ideal image quality. This can
be difficult because some imaging procedures can take up to three hours
to perform (though new equipment is available that can substantially
shorten the procedure time). And sometimes it may take awhile to
thoroughly interpret the results.
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