CT (computed tomography), sometimes called CAT scan, uses special x-ray equipment to obtain image data from different angles around the body and then uses computer processing of the information to show a cross-section of body tissues and organs. A CT scan can be used to study all parts of your body, such as the chest, belly, pelvis, or an arm or leg. It can take pictures of body organs, such as the liver, pancreas, intestines, kidneys, bladder, adrenal glands, lungs, and heart. It also can study blood vessels, bones, and the spinal cord.
A CT scan uses X-rays to make detailed pictures of structures inside of the body. During the test, you will lie on a table that is attached to the CT scanner, which is a large doughnut-shaped machine. The CT scanner sends X-rays through the body area being studied. Each rotation of the scanner provides a picture of a thin slice of the organ or area.
In some cases, a dye called contrast material may be used. If your physician recommend with contrast then the dye would be intravenously with an IV in your arm, to be able to see those areas better. For some types of CT scans you drink the dye. The dye makes structures and organs easier to see on the CT pictures.
How does a patient prepare for a CT scan and how is it performed?
You should wear comfortable, loose-fitting clothing to your exam. You may be given a gown to wear during the procedure. Metal objects, including jewelry, eyeglasses, dentures and hairpins, may affect the CT images and should be left at home or removed prior to your exam. You may also be asked to remove hearing aids and removable dental work. Women will be asked to remove bras containing metal underwire. You may be asked to remove any piercings, if possible.
You should inform the technologist if you have a pacemaker. Pacemakers do not hinder the use of CT as in MRI as long as the scanner will not be taking images repeatedly over the area of the pacemaker device in the upper chest. This is usually not an issue for cardiac CT exams.
You may be asked not to eat or drink anything for a few hours beforehand, especially if a contrast material will be used in your exam. You should inform your physician of all medications you are taking and if you have any allergies. If you have a known allergy to contrast material, or “dye,” your doctor may prescribe medications (usually a steroid) to reduce the risk of an allergic reaction. These medications generally need to be taken 12 hours prior to administration of contrast material. To avoid unnecessary delays, contact your doctor before the exact time of your exam. Also inform your doctor of any recent illnesses or other medical conditions and whether you have a history of heart disease, asthma, diabetes, and kidney disease or thyroid problems. Any of these conditions may increase the risk of an unusual adverse effect. Women should always inform their physician and the CT technologist if there is any possibility that they may be pregnant.
During the test, you will lie on a table that is attached to the CT scanner. The table slides into the round opening of the scanner, and the scanner moves around your body. The table will move while the scanner takes pictures. You may hear a click or buzz as the table and scanner move. It is very important to lie still during the test. During the test, you may be alone in the scanning room. But the technologist will watch you through a window. You will be able to talk to the technologist through a two-way intercom.
The test will take about 30 to 60 minutes. Most of this time is spent getting ready for the scan. The actual scan only takes a few seconds. The CT scan is performed by a radiology technologist and once the scan is completed, the computer generates visual images of the area of the body that was scanned.
How does a patient obtain the results of the CT scan?
After the CT scanning is completed, the computer generates visual images of the area of the body that was scanned. These images can be transferred to film (hard copy) or burned to a CD. A radiologist is a physician who is specially trained to interpret images of the body. The interpretation is transmitted in the form of a report to the physician who requested the CT scan. Your physician can then discuss the results with the patient and/or family.