Understanding Computer Assisted Tomography (CT/CAT Scan)
Assisted Tomography (CT or CAT) is a scan that provides anatomical information,
which is used to differentiate abnormal from
normal structures. It is often referred to
as the “roadmap” of the body and
is an important part of diagnosing, monitoring
and treating patients with cancer.
A CT scanner is a special x-ray machine combined
with a computer that produces cross-sectional
images, or “slices” of any part of
your head and/or body. Unlike the standard “flat” x-ray,
where some organs can block out other structures,
scan sends shows structures within each slice
on a three-dimensional surface. The scans are
also used in surgical procedures to help accurately
guide the placement of instruments or treatments.
Preparing for a CT Scan
Each type of CT scan has its own special preparations.
The most frequently performed scans are head,
chest, abdomen, and pelvis. Some scans require
patients to drink a liquid prior to the study
called a “contrast.” This makes
it easier to see the organs, blood vessels,
etc. on the pictures. If taking the liquid,
patients are asked to refrain from eating and/or
drinking for at least 2 hours prior to their
scan. Some scans also require the contrast
be administered intravenously prior to the
scan. Your doctor or nurse will review the
specific instructions for your CT scan.
The scan takes approximately 10 to 30 minutes
to complete. The length of times depends on the
number of pictures and the different angles being
taken. During this time, you will be asked to
lie still on a table that moves through a round
opening called a “gantry.” The CT
scanner is open around you, does not come in
contact with you, and is not confining. It should
not be confused with the MRI scanner that is
shaped more like a tunnel. Because X-rays are
unable to pass through metal, you may be asked
to remove jewelry, glasses, or clothing, which
have zippers, snaps, etc.
Do people experience any reactions because
of a CT scan?
Some individuals may need special blood tests
when receiving the contrast intravenously. You
should notify the technologist about previous
allergies (especially to iodine), and previous
reaction to X-ray dye, any renal problems, or
diabetes. Most patients have no issues related
to having a CT.
For more information, visit the Radiology
at Pennsylvania Hospital web site or call
1-800-789-PENN (7366). You can also request
an appointment online.