CT Scan ("Cat Scan")

OncoLink Team
Last Modified: July 16, 2018

What is a CT scan?

A CT scan is a medical test that takes pictures of organs inside your body using x-ray technology. The pictures are taken in a cross-sectional manner, meaning the pictures are "slices" of the body, from the top of the area being looked at to the bottom. It is as if you were slicing the body like a loaf of bread. These slices help the radiologist to look at organs, tissues and bones in small parts. They can also be put together to create 3D images.

A CT scan can be done quickly, so it can be used in an emergency. An example is using a CT of the head to check for bleeding on the brain. CT scans are often used to figure out if a person has cancer, and if they do, if it has grown. After cancer treatments, CT scans are used to see how well the treatments worked.

How do I prepare for a CT scan?

How you prepare for a CT scan depends on what is being scanned, or if contrast (dye) is being used. If IV contrast is being used, you cannot eat for 4 hours before to the test. This is because the IV contrast can cause a reaction or upset stomach. If the scan will involve looking at the stomach or bowel, you may be given contrast that you drink. This is done to be able to see the difference between the bowels and other structures. Contrast can also be given through an enema.

If you are receiving IV contrast, it will be given either before or during the test. It does not hurt, but some patients do feel warm or flushed after it is given, and this is normal. Some patients have allergic reactions to contrast. If you have ever had a reaction, you should tell your provider before the exam. You may be given steroids and Benadryl to prevent any reaction. 

How is this test performed?

A CT scan is done while you lie on a flat table. This table moves in and out of a ring that contains the “camera”. It is important that you lie still during the test. You may be asked to hold your breath for short periods of time. The test will take anywhere from 15-45 minutes. You will be by yourself in the room but a technician will be able to communicate with you. The test is not painful, but some people find it difficult to lie flat and still. The technician will help you get comfortable.

During the test, X-rays go through the patient and hit a detector behind the patient. As the X-rays pass through the patient, some are deflected by bones and soft tissue. These X-rays create a picture. The computer then processes these to create a slice-by-slice picture of the patient. A radiologist, which is a doctor who specializes in looking at different types of images, looks at the scan and creates a report.

Picture of a CT Scanner

How do you receive the results of your CT scan?

The radiologist writes a report for the provider who ordered the CT scan. The report provides information about the patient, the reason for the test, and if contrast was given. The report will detail both normal and abnormal findings. Your provider will be able to discuss your results with you.

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