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What is a CT or CAT scan?
A CT or CAT scan is a diagnostic imaging procedure that uses a
combination of x-rays and computer technology to produce cross-sectional
images (often called "slices"). A CT scan shows detailed images of any part
of the body, including the bones, muscles, fat, and organs. CT scans are
more detailed than general x-rays. CT scans also minimize exposure to
radiation. In computed tomography, the x-ray beam moves in a circle
around the body. This allows many different views of the same organ or
structure, and provides much greater detail. The x-ray information is sent
to a computer that interprets the x-ray data and displays it in
2-dimensional form on a monitor. While many images are taken during a CT
scan, in many cases, the patient receives less radiation exposure than with
a single standard x-ray.
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 under study to be seen more
clearly.
Let your physician
know if you have ever had a reaction to any contrast dye, or if you are
allergic to iodine or seafood. If you are pregnant or think you may be
pregnant, you should notify your physician.
How is a CT or
CAT scan performed?
CT scans can be performed on an outpatient basis, unless they are part
of a patient's inpatient care. Although each hospital may have specific
protocols in place, generally, CT scans follow this procedure:
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When the patient arrives for the CT scan, he/she will be asked to remove
any clothing, jewelry, or other objects that may interfere with the scan.
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If
the patient will be having a procedure done with contrast, an intravenous
(IV) line will be started in the hand or arm for injection of the contrast
medication. For oral contrast, the patient will be given medication to
swallow.
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The
patient lies on a scan table that slides into a large, circular opening of
the scanning machine.
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The
CT staff will be in another room where the scanner controls are located.
However, the patient will be in constant sight of the staff through a
window. Speakers inside the scanner will enable the staff to communicate
with and hear the patient. The patient will have a call bell so that
he/she can let the staff know if he/she has any problems during the
procedure.
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As
the scanner begins to rotate around the patient, low-dosage x-rays pass
through the body for short amounts of time.
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The
x-rays absorbed by the body's tissues are detected by the scanner and
transmitted to the computer.
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The
computer transforms the information into an image to be interpreted by the
radiologist.
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It
is very important that the patient remain very still during the procedure.
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The
technologist will be watching the patient at all times and will be in
constant communication.
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The
patient may be asked to wait for a short period of time while the
radiologist examines the scans to make sure they are clear. If the scans
are not clear enough to obtain adequate information, the patient may need
to have additional scans performed.
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