CT (Computed Tomography)

Computed Tomography (CT)

What is Computed Tomography (CT)?

A computer Tomography (CT) scan is a precise, simple and safe examination that creates a cross-sectional image of a specific anatomical part of the body. A thin beam of x-rays is read and recorded by an electronic detector, then fed into a computer. The computer constructs an image based on the data, which then may be transferred to film. Contrast media are substances given intravenously or orally to assist in viewing a particular area.

Methodist Willowbrook Hospital has 2 state-of-the-art 64-slice CT scanners with the ability to perform a wide array of specialized procedures. These scanners provide detailed images of the anatomical system in just seponds and allow for quick interpretation and diagnosis. With four times as many detectors as a typical multi-detector CT scanner, the 64-slice scanners provide sharp, clear, three-dimensional images, including 3-D views of the blood vessels. They gather high-resolution images of a heart, brain, or a pair of lungs in about five seconds; a scan of the whole body takes about 30 seconds. This new technology minimizes radiation dosage to patients, especially children.

Also within the Methodist CT department are dedicated computer workstations that allow for advanced specialized post-processing for 3-D imaging. CT of the Coronary Arteries provides unsurpassed visualization that was previously only available during an invasive cardiac catheterization procedure.

There are two CT scanners for prompt patient care and rapid work-in of urgently needed imaging studies for unscheduled outpatients.

The CT Department provides comprehensive services, including needle aspiration and biopsy and other invasive procedures. A radiologist is on-site to monitor and guide the CT diagnostic, interventional, and therapeutic procedures.

How is a CT scan performed?

CT scans can be performed on an outpatient basis, unless they are part of a patient's inpatient care. Although each hospital may have specific protocols in place, generally, CT scans follow this process:

1. When the patient arrives for the CT scan, he/she will be asked to remove any clothing, jewelry, or other objects that may interfere with the scan.
2. If the patient will be having a procedure done with contrast, an intravenous (IV) line will be started in the hand or arm for injection of the contrast medication. For oral contrast, the patient will be given medication to swallow.
3. The patient lies on a scan table that slides into a large, circular opening of the scanning machine.
4. The CT staff will be in another room where the scanner controls are located. However, the patient will be in constant sight of the staff through a window. Speakers inside the scanner will enable the staff to communicate with and hear the patient.
5. As the scanner begins to rotate around the patient, low-dosage x-rays pass through the body for short amounts of time.
6. The x-rays absorbed by the body's tissues are detected by the scanner and transmitted to the computer.
7. The computer transforms the information into an image to be interpreted by the radiologist.
8. It is very important that the patient remain very still during the procedure.
9. The technologist will be watching the patient at all times and will be in constant communication.

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Are there special preparation requirements for the exam?

You should wear comfortable, loose-fitting clothing for your CT scan. Avoid clothing with snaps or zippers. The arrival time for your appointment will be based on the type of CT scan you are having. Some exams require that you drink a contrast material 1–2 hours prior to your exam. How you prepare also depends on which part of your body is being scanned. You may be asked to remove your clothing and dress in a hospital gown. You will also need to remove any metal objects such as jewelry that might interfere with the image results. If you are required to have a contrast material before you scan, it is usually to help emphasize blood vessels or other structures while blocking others. You will either have the contrast material by injection, mouth or enema. If your test involves contrast medium, your healthcare provider may ask you not to eat for 4 to 6 hours before the test because the contrast medium can cause nausea.

Inform your technologist if you:

• Have a known allergy to the contrast dye or material or any substance that contains iodine
• Have diagnosed heart failure
• Have diabetes and are on medication
• Have history of kidney problems
• Become anxios in confined spaces or are claustrophobic

If there is a chance that you may be pregnant, notify your healthcare provider and/or x-ray technologist

What should I expect during the CT procedure?

The procedure requires a few basic steps, although some aspects may vary depending on the examination you will be receiving.

1. The technologist will be in constant communication with you during the procedure through a two-way intercom.
2. You will lie on a tablet that is connected to the CT scanner.
3. The area of interest will be positioned in the middle of a large, doughnut-shaped scanner ring or gantry. The gantry is not enclosed, thus claustrophobia is usually not an issue.
4. Please pay close attention to the instructions given to you and please refrain from any unnecessary movement. Body shifts may cause the images to blur, thus causing portions of the exam to be repeated.
5. The table will be moving in small increments. You will feel this slight movement and hear a low noise. The noise is due to the gantry rotating around you and is perfectly normal.

How long will the exam take?

The length of the examination will vary from ten minutes to forty-five minute, depending upon the specific examination requested by your physician.

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Is CT for everyone?

Although CT is an effective diagnostic tool, certain medical conditions may exclude its use. Please inform your physician and his staff at the time of scheduling if any of the following apply to you:

• Prior allergy to iodine, contrast media or shellfish
• Diabetes
• Kidney problems
• breast feeding or pregnancy

Reminders before the examination

• If you are pregnant or think you may be pregnant, please inform your physician and our personnel prior to your exam being scheduled.
• Please arrive 30 minutes prior to your scheduled procedure time to complete paperwork and change clothes, if necessary.
• Please wear loose-fitting clothes without zippers or snaps; metal objects create artifacts on the images.
• If contrast will be used, do not consume food or beverages four hours prior to the procedure.

Weight limit

400 pound weight limit.

For more information about Willowbrook Imaging & Diagnostic Services at the Methodist Willowbrook Hospital, please call 281-737-1234.

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