CT (Computed Tomography)
Detailed information about CT can be found at the American College of Radiology’s website RadiologyInfo.org
In simplified terms, a CT is a type of xray. During CT, a thin beam of x-rays circles completely around the body, collecting a 360-degree view of the area being examined. This information is fed into a computer that produces a two dimensional cross sectional "slice" of a portion of the body. Multiple slices are taken to cover the area of the body to be examined. These studies enable the radiologist to see structures inside the body, which makes diagnosis and treatment more accurate.
How do I prepare?
You may be asked to drink a special oral contrast material before the exam to improve visualization of your intestines. You should have nothing else by mouth for 4-6 hours prior to the exam.
What should I wear?
You should wear comfortable, loose-fitting clothing for your CT exam. Metal objects can affect the image, so avoid clothing with zippers and snaps. You may also be asked to remove hairpins, jewelry, eyeglasses, hearing aids and any removable dental work, depending on the part of the body that is being scanned. You may be asked to change into a gown.
What should I expect during the exam?
A technologist with special training in CT will perform your exam. Before the exam the technologist should explain the procedure to you and answer any questions that you have. He may start an IV catheter in your arm. You will be asked to lie on the CT scanner. The technologist will leave you alone in the CT room during the exam, but will be able to see you and talk to you at all times. The table you are on will move in and out of the scanner during the exam. The machine will not touch you, and you will not feel the x-rays, but you will hear whirling and clicking noises. The technologist may inject contrast material through your IV during the examination to improve visualization of the organs in the body. If so, you may feel hot and flush during the injection. You may have a metallic taste in your mouth. This is expected. You may be asked to you’re your breath, usually for 20 seconds or less. You should hold your breath and be as still as possible during the exam or your pictures may be blurry and the exam may need to be repeated.
How long will it take?
You should allow approximately 30 minutes for the exam, although most of that time is in preparation. The amount of time the machine is actually scanning is usually only a minute or two.
What if I am pregnant?
You should definitely inform both your doctor and the technologist if you are pregnant. Under most circumstances, CTs should NOT be performed on pregnant women do to the risk of radiation exposure to the baby. Your doctor may consult with the radiologist to determine if another study would be more appropriate for you.
Are there any limitations after the exam?
No. You may return to your normal activities, unless instructed otherwise by your doctor.
Is the exam safe?
Generally yes, but you should be aware of several risks.
- Radiation Exposure: CTs involve exposure to a small amount of radiation. Generally, it is considered that the small risk of the radiation exposure is outweighed by the potential benefits of the information gained by the exam, however you should consider discussing the need for the exam with your referring physician. Other tests may be available to you.
- Allergic Reaction: Iodinated IV contrast material is frequently used with CT. These contrast agents are generally safe, but, like all medications, side effects can occur. The incidence of side effects has decreased considerably over the years as newer contrast medicines have been developed. However, a small percent of patients may be allergic to the intravenous agent. Allergic reactions are usually mild (itching, flushing) but occasionally may be severe. If you have had allergic reactions to these agents before, or if you have asthma or multiple allergies, you may be at higher risk for a reaction. Let your doctor know if you have any of these conditions that would increase your risk.
- Kidney Failure: Iodine contrast can also rarely cause kidney toxicity in people with certain medical conditions, which include but are not limited to: kidney failure, diabetes, multiple myeloma, severe dehydration, hyperuicemia (seen with gout), and heart failure. If you fall into one of these categories, or if you are over age 60, a blood test may be needed prior to the study to measure your kidney function.
How do I get the results?
A radiologist will review and interpret the images from your exam. He or she will provide a written report to your referring physician which includes a description of the findings, any diagnosis that can be made from the exam, and a recommendation for further studies, if needed. Reports are usually available within 24 hours of completion of the examination, and are generally received by your physician within two working days. A report may be delayed if we are awaiting studies from an outside facility for comparison purposes. If the results are urgent or if you are seeing your doctor on the same day as your exam, your doctor may request that a preliminary report be phoned or faxed.
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