What is a CT Scan?
CT stands for computerized tomography, which refers to the way this exam is performed. In actuality, a CT scan is an X-ray procedure enhanced by sophisticated computer software. This results in a cross-sectional view (referred to as a "slice") of a particular part of your body. This cross-sectional image is created when the scanner revolves around you during the imaging process-which is why CT scans are described as helical or spiral.
CT provides a much more detailed image of the body's structures compared to routine X-ray because dense tissues, e.g., bone, can block the view of other areas during a routine X-ray. Aided by the computer, a CT scan is able to put together the different "slices" and clearly show both bone and soft tissues. CT scans are particularly useful for imaging of the chest, abdomen and pelvis as well as the spine and other bony structures in certain patients.
Undergoing a CT scan exposes the body to a small dose of radiation. The exact dose of radiation depends on several factors, including how much of the body is to be imaged. The CT scanners at Torrance Memorial imaging centers are optimized to provide the lowest-dose radiation possible while ensuring optimal image quality. Like all other imaging equipment at Torrance Memorial, our CT scanners are licensed and maintained to the highest FDA standards.
CT scanning is one of the most useful imaging technologies available for detecting and characterizing malignancy and other abnormalities of many bodily structures and organs. Concerns remain, however, about the long-term safety of CT since undergoing a CT scan exposes the patient to low dose radiation. The long-term effects of CT-related radiation exposure are still under study by scientists. Evidence suggests that those at greatest risk for a future cancer caused by CT radiation exposure are those who receive repeated CTs during childhood. It is likely that for individuals with known or suspected cancer or other abnormality, the potential benefit of CT outweighs the risk of future malignancy.
How do I prepare for the scan?
Metal objects such as jewelry, eyeglasses and dentures may affect CT images so should be removed prior to the exam. You may also need to remove hearing aids and removable dental work.
Sinus - no prep
Brain/chest/extremities without contrast - no prep.
Brain/chest/extremities with contrast - no prep.
Abdomen - Oral contrast material is commonly ordered before a CT scan of the abdomen or pelvis. The contrast enhances the visibility of the intestinal and other soft tissue structures. Drink the oral contrast (you may pick this up at the Polak Imaging Center reception desk in the lobby) 1 hour prior to your scan. To get the best scan results, it is important that you drink all of the contrast liquid over about a 30 minute time period. You may take your usual at-home medications as prescribed.
Abdomen and Pelvis - Same as abdomen only, except the oral contrast should be ingested 2 hours prior to the scan.
What will the exam be like?
The CT scanner consists of a large donut-shaped machine and an X-ray table. You will lie on the table. The scan is painless and non-invasive. A series of pictures is taken as the table is slowly slid into the large opening of the scanner. You may be given an IV injection of contrast material (dye) into your arm which enhances the visibility of the structures within the body. The technologist sits at a monitor to conduct the scan and can see a full view of you throughout the exam. The room contains an intercom so the technologist can communicate with you as needed.
Depending on the instructions of your physician who requested the scan, contrast material (dye) may be necessary to enhance the visibility of the structures within your body. Contrast material may be taken by mouth, administered by IV injection in your arm by the RN, or be administered by both routes, depending on the ordering physician's request and the condition you are being evaluated for. During the IV injection, you may feel warm; some patients notice a slight metallic taste in their mouth. These sensations are normal and last only a minute or two. Let the technologist know immediately if you begin to itch, feel any shortness of breath, or are otherwise uncomfortable in any way, since it is possible, although the risk is low, that you could have an allergic reaction.
During the scan you may hear buzzing while the scanner is creating the images. You will be in constant view by the technologist who sits behind a leaded glass window. The room has an intercom system so that you can communicate with the technologist as needed.
After the exam
You may resume your normal activities, including driving.
Drink plenty of fluids for about 24 hours after the exam to flush your system of the IV contrast material. No radiation remains in your body after the scan is over.
Nursing mothers should wait 24 hours after receiving contrast material before resuming breast feeding.
How will I learn of the results?
Contact your physician who requested the scan to discuss the results.
- Tell your doctor, technologist or nurse if you are pregnant or think you might be.
- Tell your doctor, technologist or nurse if you are allergic to iodine or have any other allergies.
- Bring a list of current medications when you come to your scan appointment.