Frequently Asked Questions
What is General
medicine is a subspecialty within radiology. It comprises diagnostic examinations
that result in images of body anatomy and function. The images are developed
based on the detection of energy emitted from a radioactive substance
given to the patient. Radiation to the patient is, generally, similar
to that resulting from standard x-ray examinations.
What are some common uses of the procedure?
Nuclear medicine images
can assist the physician in diagnosing diseases. Tumors, infection and
other disorders can be detected by evaluating organ function. Specifically,
nuclear medicine can be used to:
Analyze kidney function
Image blood flow and
function of the heart
Scan lungs for respiratory
and blood-flow problems
Identify blockage of
the gallbladder (cystic duct)
Evaluate bones for fracture,
infection, arthritis or tumor
Determine the presence
or spread of cancer
Locate the presence of
Measure thyroid uptake
to detect hyperthyroidism or hypothyroidism
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.
What does the equipment look like?
most nuclear medicine examinations, you will lie down on a scanning table.
Consequently, the only piece of equipment you may notice is the specialized
gamma camera used during the procedure. It is enclosed in 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 structure similar
in appearance to a computed tomography (CT) scanner. Often, the camera
is beneath the table out of view.
A nearby computer console,
possibly in another room, processes the data from the procedure.
How does the procedure work?
You are given a compound,
usually intravenously but sometimes orally, containing a small amount
of a radioactive substance that localizes in specific body organ systems.
This compound, called a radiopharmaceutical or tracer, eventually collects
in the organ and gives off energy as gamma rays. The gamma camera detects
the rays and works with a computer to produce images and measurements
of organs and tissues.
How is the procedure performed?
A radiopharmaceutical is
administered 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. Imaging time varies, generally ranging from
20 to 45 minutes.
that is used is determined by what part of the body is under study since
some compounds collect in specific organs better than others. 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 organ under
study, thus the wide range in scanning times.
You must remain as still
as possible during imaging. If the gamma camera is moved slowly along
the body, the resulting image is called a planar scan. Sometimes sequential
images are obtained to show how an organ functions over time.
After the procedure, a
physician with specialized training in nuclear medicine checks the quality
of the images to ensure that an optimal diagnostic study has been performed.
What will I 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 special studies, a catheter
may be placed into the bladder, which may cause temporary discomfort.
Lying still on the examining table may be unpleasant for some patients.
loses its radioactivity generally over 24 hours. It passes out of the
body in the urine or stool.
Who interprets the results and how do I get
Most patients undergo a
nuclear medicine examination because a referring physician has recommended
it. A physician who has specialized training in nuclear medicine 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
What are the benefits vs. risks?
Nuclear Medicine procedures
will result in exposure to a small dose of radiation. However, the doses
of radiopharmaceutical administered are the smallest possible. Nuclear
medicine has been used for more than three decades, and there are no
known long-term adverse effects from such low-dose studies.
Allergic reactions to the
radiopharmaceutical can occur, but are extremely rare.
What are the limitations of General 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, though new equipment
is available that can substantially shorten the procedure time.
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