Computed Tomography, sometimes called a CAT scan, is a noninvasive, painless medical test that helps physicians diagnose and treat medical conditions.  CT is a special type of exam that uses x-rays to produce detailed pictures of inside of the body.  CT uses a narrow x-ray beam that is directed through the body and recorded by several detectors.  This information is used to produce multiple cross-sectional images or "slices" of the area being studied.  Dense tissues, such as bone, appear white on CT images.  Less dense tissues, such as brain tissues or muscle, appear in shades of gray.  Air-filled spaces, such as in the bowel or lungs, appear black on a CT image.

 

     During a CT scan, the area being imaged is positioned inside a ring or "gantry" that is part of the CT scanner.  The ring can tilt and the x-ray devices within it can rotate to obtain the views needed.  CT can be used to obtain information about almost any body part. 

 

     The amount of radiation used in CT exams is comparable to the amount of radiation used in standard x-ray procedures.  However, there is much more information obtained from a CT scan than from standard x-rays. 

 

     A dye that contains iodine (contrast material) is often injected into a vein during a CT scan if your scan is ordered with contrast by your doctor.  The contrast allows blood vessels and certain structures to enhance and become for visible on the CT images.  Sometimes, contrast is given by mouth (orally) for abdominal CT scans. 

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How do I prepare for my CT scan?

 

Tell your doctor if you have any allergies, especially to iodine or x-ray contrast, since for some CT exams an iodine dye (or contrast) is given intravenously. If you are allergic, medication will be prescribed for you to take prior to the testing.

 

     If you have a history of kidney problems or diabetes, blood tests (creatinine, blood urea nitrogen) will be done before the CT scan to check that your kidneys are functioning properly. The intravenous contrast material used during a CT scan can cause kidney damage in people with poor kidney function.

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     Tell the technologist if you are on Metformin for diabetes control.

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     Tell your doctor if you are, or suspect you might be pregnant.

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     You may be asked not to eat or drink for four to six hours prior to your exam.

 

What can I expect during my CT scan?

     

     A registered technologist will discuss the procedure with you and answer any questions you may have.  A radiologist will review your medical history and tailor the CT study specifically for your medical problems. 

 

     For most abdominal CT scans, you will be given a cup of contrast to drink thirty to sixty minutes prior to the exam. For some exams, contrast will be injected into a vein in your arm before or during a procedure. 

 

     The technologist will position you on the exam table in a donut-shaped gantry.  At times during the exam, the table will move, and you will hear the sound of the x-ray tube circling your body. At all times, the technologist will be able to see you and communicate with you on a two-way intercom.  Most procedures take approximately thirty minutes. 

 

     The technologist will show your images to the radiologist, and additional images will be obtained if needed. 

 

What will happen following my CT scan?

     

     After your CT scan, you may resume your normal activities, diet, and medications, unless instructed otherwise by the technologist or your doctor.  Any contrast given for your exam will be eliminated in a day or two, and it is important to drink a lot of water if you have had a contrast CT exam.  Your examination will be reviewed and reported on by a radiologist, and the results will be sent to your doctor. 

 

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