Diagnostic
Services
Radiology
Services - Computed
Tomography (CT SCAN) |
What
does the equipment look like?
The CT scanner is a large, square machine with a hole in
the center; it looks like a big doughnut. You will lie still
on a table that can move up or down, and slide into and
out from the center of the hole. Within the machine, an
x-ray tube on a rotating circular frame with a detector
on the opposite side moves around your body to produce the
images. It may make clicking and whirring noises as the
arm moves.
How
is the procedure performed?
The technologist begins by positioning you on the CT Table.
Your body may be supported by pillows to help you keep still
and in the proper position during the procedure. As the
study proceeds, the table will move slowly into the opening
in the center of the CT scanner. Depending on the area of
your body being examined, the increments of movement may
be so small that they are almost undetectable or large enough
that you will feel the sensation of motion.
A
CT examination often requires the use of different contrast
materials to enhance the visibility of certain tissues or
blood vessels. The contrast material may be injected into
your blood stream, given orally, or administered by enema,
depending on the type of examination. Before administering
the contrast material, the radiologist or technologist will
ask whether you have any allergies, especially to medications
or iodine, and whether you have history of diabetes, asthma,
a heart condition, kidney problems or thyroid conditions.
These conditions may indicate a higher risk of reaction
to the contrast material or potential problems eliminating
the material from your system after the exam. Nursing mothers
should wait for 24 hours after contrast material is administered
before resuming breastfeeding.
How does the procedure work?
In many ways, CT scanning works like other x-ray examinations.
Very small, controlled amounts of x-ray radiation are passed
through the body, and different tissues absorb the radiation
at different rates. Each time the x-ray tube and detector
make a 360-degree rotation and an x-ray passes through your
body; the image of a thin section or slice is acquired.
During each rotation, the detector records about 1,000 image
slices.
A
CT examination usually takes from 15 to 30 minutes. When
the procedure is over, you may be asked to wait until the
images are examined to determine if more images are needed.
