Department of Neurology
Department of Neurosurgery
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The CT: Computed Tomography Test
University of Iowa Department of Neurology
Peer Review Status: Internally Peer Reviewed
First Published: 1998
Last Revised: March 2004
A CT scan is a method of taking pictures inside your body. A scanner produces a series of images, many of them that do not show up on conventional x-rays. The scanner takes these pictures while you rest on a scanning couch.
What is it?
- a method of taking pictures inside your body
- a scanner produces a series of images, many of which would not show up on conventional X-rays
- for some scans, a dye will be injected to outline blood vessles or organs so that they can be seen more easily
How long does it take?
- about 30 to 90 minutes
- scans of the head may take longer
Why is a CT performed?
- to show conditions inside your body not detected by conventional X-rays
Does it hurt?
- a CT scan is completely painless. However, some patients may experience slight discomfort from the injection of a dye
- there are no after-effects from the CT scan. You should feel just as you did before the scan
Where is it conducted?
- the CT/Interventional Reception Area
- 3rd level of Colloton Pavilion
How many CTs are conducted each year?
What is a CT scanner?
- a large, donut-shaped chamber that houses an X-ray tube and a detector that sends information to a computer
- you will lie on a couch which will gradually slide into the chamber as the scanner takes its pictures
What should you do to prepare for the test?
- if a dye is to be used during the scan, you may be asked not to eat for at lest 3 hours before the scan
- do not drink anything for one hour before the test
- give a complete list of any medications you are currently taking, both prescribed and nonprescription, to your doctor
- tell your doctor or radiologist all details concerning the following aspects of your current health:
- if you are pregnant
- if you are diabetic
- if you are allergic to any foods or drugs
- if you had any previous side effects to a contrast medium or dye in the past
- if you have had or are presently being treated for an infection anywhere in your body
- you must put on a hospital gown and remove watches, jewelry, or any other metal objects you might be wearing
- you will lie down on the scanning table
- you will be positioned comfortably, generally with your arms at your sides and your head cradled in the headrest. If you have long hair, it will be tucked into the headrest.
How is it performed?
- the part of your body to be scanned must be positioned in the middle of the scanner ring
- you will be asked to keep as still as possible during the scan. You may breathe normally throughout the scan.
- if a contrast medium (dye) is used, the radiologic technologist will probably take some preliminary scans before the radiologist injects the dye
- you will hear clicking and buzzing noises as the mechanism in the scanner moves around your body.
What if I feel sick in the scanner?
- there is no need to worry
- the radiologist and the technician can see you through an observation window
- the scanner has a two-way intercom so that you can talk with the technologists
- someone is always available to make you comfortable
After the test
- the images will be reviewed for quality, If they are acceptable, you may return to your hospital room or go home, unless given other instructions from the doctor.
- if more images are needed, they will usually be taken right away
- unless you have other tests scheduled, you may eat normal meals after the exam
- drink plenty of fluids. They will help eliminate the contrast medium from your body (if one was used)
- when the test results are complete, you will be informed of them either at the time of your visit, or from a copy of the letter sent to your personal physician