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CT (CAT Scan)
What is Computed Tomography?
The computed tomography scan (also referred to as CT or CAT scan)
is a sophisticated CT x-ray tube that rotates in a circle around a
person taking many pictures of the body and anatomy as it rotates. The
multiple images are reconstructed by a computer in axial slice images,
similar to the way a loaf of bread is sliced. Each slice may then be
examined separately. This modality can detect many conditions that do
not show up on less sophisticated tests.
Computed tomography is
a radiographic technique. While x-rays pass through the person as in
standard radiography, the x-ray beam in CT is "fired" from multiple
angles to generate each image. Standard x-rays are detected by film,
but in CT they strike radiation detectors that produce a tiny
electrical impulse proportional to the intensity of the x-ray beam. The
electrical current is digitized and registered in the form of
computer-stored data.
One of the advantages of CT is that
computer-stored data can be recreated and manipulated with differing
degrees of photographic contrast...without requiring reexamination of
the person.
The data and sensitivity of the radiation detectors (as
opposed to film images) result in greater sensitivity to small
radiographic density changes. CT, therefore, can detect slight
variations in tissue density. CT is a "non-contact" procedure and is
not inhibited by surgical dressings or drains, skin lesions, or wounds.
CT
may be used to check for bleeding, detect tumors, clots, ruptured
disks, organ size/shape, and to evaluate a variety of disease
processes.
How should I prepare?
CT appointments may be scheduled at our Puyallup, Sunrise and
Bonney Lake Imaging Centers, in the Radiology Departments of our
hospital locations or MultiCare partner clinic sites in Covington,
Auburn, Kent, Northshore and Gig Harbor. Please allow 30-60 minutes for
the examination.
If there is a chance that you may be pregnant, please inform our staff at the time you schedule your appointment.
Preparation
for your CT may vary according to the type of examination performed.
The Receptionist will give you instructions when your examination is
scheduled.
Depending if your referring physician has ordered an examination requiring oral or IV contrast,
you may be asked to limit your food and/or liquid intake for a specified period prior to the examination.
Additionally,
you may be asked to pick up a pre-examination dose of oral contrast
before your appointment date. Or, you may need to arrive early the day
of the exam to drink the oral contrast on site.
Wear
comfortable, loose-fitting clothing the day of your CT exam. Avoid
wearing any metal objects such as jewelry, hairpins, earrings, or other
similar items. During the exam you will be asked to take off your
glasses, hearing aids, or any removable dental work.
Also,
please make arrangements to keep your children at home on the day of
your appointment. There are no childcare services onsite...and due to
the presence of radiation, children are not allowed to enter exam rooms
during imaging procedures.
What Should I Expect?
The CT machine resembles a large standing donut (called the gantry)
with a table positioned through its center. You will be asked to lie as
still as possible on the table as it is moved slowly into the gantry.
The gantry houses the rotating x-ray tube and detectors. You may see
the CT rotating around you, and hear the CT machine make a whirring
sound as it moves around your body. There is no discomfort associated
with the CT scan itself.
The technologist will not be in the
room with you, but she/he can see, hear, and speak to you at all times
throughout the procedure.
The IV contrast is usually injected
with a motor driven power injector. If the needle becomes dislodged
from the vein, irritation in the skin may occur. There is also a risk
of allergy to the contrast material resulting in hives, itching,
wheezing, or shock. Please tell the technologist immediately if you
begin to feel itchy or short of breath.
Pretreatment with
Benadryl and Prednisone usually eliminates reaction in potentially
allergic patients. (Read more about Contrast Agents in this procedure
section of our website.)
Results are usually available 3 working
days after the procedure. Please contact your referring physician for
results at that time.
If you received contrast agents, you may
experience nausea, headache or dizziness after the procedure is
completed. It is very important to increase the amount of water you
drink for a few days after the exam. Notify your personal physician or
healthcare provider if your symptoms persist.
Medical Imaging Northwest is accredited by the American College of Radiology (ACR) in CT.
Which locations provide this service?
- Puyallup Imaging Center
- Sunrise Imaging Center
- Bonney Lake Imaging Center
- MultiCare Good Samaritan Hospital
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