Friday, January 28, 2022

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CT/CAT (Computerized Axial Tomography)

CAT Scans, also called CT scans, were developed in the 1970s.  They are a very advanced X-Ray procedure that generate images that are ‘slices’ of the body by moving the X-Ray generating tube completely around the body and using a sophisticated computer to convert the results into images.  Generally, the tube and detectors rotate around the body while the table moves through the machine; this is sometimes called a ‘spiral CT’, but the images are still generated in ‘slices.’  The results from your study are a series of cross-section images of your body, like slices in a loaf of bread.  In some cases the images can even be merged into a 3D view of the body.

To enhance the images, we will often use a ‘contrast’ media.  For many studies this is an iodine solution that is injected intravenously. 
For some gastrointestinal studies (GI), we use a barium solution, which is either drunk like a milkshake for upper GI, or given in an enema for lower GI studies.

Because CT scans use X-Rays, there is some radiation exposure associated with them.  This exposure is higher that a typical single X-Ray image.  We work very hard to minimize your exposure, so we use the lowest exposure that will get the job done.

There are often special instructions to be followed before and after the procedure, so carefully read and follow the instructions provided to you by your doctor and our center.  Be sure to carefully note all your allergies on the paperwork you fill out, since the contrast media can cause issues in a small number of cases.  If you are claustrophobic or have issues with being in a confined space, please let us know, as the opening it the CT scanner is rather restrictive; we can take steps to make you more comfortable.

A CT/CAT (Computerized Axial Tomography) scan is a simple, non-invasive procedure that enables medical professionals to quickly and safely obtain sophisticated and accurate diagnostic information on your brain, chest, abdomen, pelvis, spine and extremities.

The first thing you will notice when you enter the CT scan examination room is the CT scan machine itself - a table surrounded by a large donut shaped cylinder. During the exam, you simply lie still on the table as a technologist slowly advances the table into the proper position. The cylinder will rotate slowly aorund the table, as thin x-ray beams take cross sectional "snapshots" of the area of the body being examined.

Don't be concerned if you hear clicking sounds as the cylinder rotates and the pictures are taken - that's simply the X-ray camera and the cylinder gears at work.


If you are or could be PREGNANT or if you have asthma, you should tell your physician before having any type of CT scan. You should also let your physician know if you have ever had a reaction to a contrast agent or if you have any allergies to food, especially shellfish.


1) How does a CT scan differ from a traditional X-ray? 

CT scans can be up to 100 times more sensitive than conventional X-rays so radiologist can distinguish subtle differences in soft tissues that may not be detected with regular X-rays

2) Is the contrast agent or "dye" painful?

No, though some people feel a warm sensation as it enters the body. If you feel any discomfort during the exam or have had a reaction to a contrast agent before or if you are allergic to shellfish, you should inform the technologist or your physician.

3) Who performs the exam?

The procedure is done by a technologist and/or a radiologist both specially trained to conduct these types of tests.

4) Should I be concerned about the radiation associated with the X-rays being taken during the CT scan?

No. CT scans require very low doses of radiation that are well within safe limits. You should also keep in mind that the value of the information gathered during a CT scan far outweighs any risk.
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