Computed tomography (CT) scans are imaging tests that may be done to help diagnose tumors, investigate internal bleeding or check for other injuries or damage.
If you need a CT scan, you can rest assured that Stanford Health Care - ValleyCare offers the latest advances in CT technology, including computed tomographic angiography (CTA), which is used to obtain images of blood vessels.
How a CT Scan Works
A CT scan uses a combination of x-rays and computer technology to produce cross-sectional images of the body, both horizontally and vertically. The scan shows detailed images of any part of the body, including the bones, muscles, fat and organs. CT scans are more detailed than standard x-rays.
CT scans may be done with or without contrast. "Contrast" refers to a substance taken by mouth or injected into an intravenous (IV) line that causes the particular organ or tissue under study to be seen more clearly. Contrast examinations may require you to fast for a period of time before the procedure. You will need to let your physician know if you have ever had a reaction to any contrast dye or if you are allergic to iodine or seafood. If you are pregnant or think you may be pregnant, you should notify your physician.
What to Expect During a CT Scan
CT scans are normally performed on an outpatient basis, unless they are part of a patient's inpatient care. Generally, CT scans require you to remain still during the procedure, which lasts an average of 10 to 20 minutes.
When you arrive for the CT scan, you will be asked to remove any clothing, jewelry or other objects that may interfere with the scan. Remember to tell the radiologist if you are allergic to iodine or other materials, or if you are pregnant.
Here's a look at some of the steps that will take place during the scan:
- If you are having a procedure done with contrast, an IV line will be started in the hand or arm for injection of the contrast medication. For oral contrast, you will be given medication to swallow.
- You will lie on a scan table that slides into a large, circular opening of the scanning machine. It is very important that you remain still during the procedure.
- The CT staff will be in another room where the scanner controls are located. However, you will be in constant sight of the staff through a window. Speakers inside the scanner will enable the staff to communicate with and hear you.
- As the scanner begins to rotate around you, low-dosage x-rays will pass through your body for short amounts of time.
- The x-rays absorbed by your body's tissues will be detected by the scanner and transmitted to the computer.
- The computer will transform the information into an image to be interpreted by the radiologist.
- You may be asked to wait for a short period of time while the radiologist examines the images to make sure they have all the information they need for an accurate diagnosis. If the scans are not clear enough to obtain adequate information, you may need to have additional scans performed.