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.
CT imaging is particularly useful because it can show several types of tissue—lung, bone, muscle, organs, and blood vessels—with great clarity. Using specialized equipment and expertise to create and interpret CT scans of the body, radiologists can more easily diagnose problems such as cancers, cardiovascular disease, infectious disease, trauma and musculoskeletal disorders.
Because it provides detailed, cross-sectional views of all types of tissue, CT is one of the best tools for studying the chest, abdomen, and pelvis. It is often the preferred method for diagnosing many different cancers, including lung, liver and pancreatic cancer, since the image allows a physician to confirm the presence of a tumor and measure its size, precise location and the extent of the tumor's involvement with other nearby tissue. CT examinations are often used to plan and properly administer radiation treatments for tumors, to guide biopsies and other minimally invasive procedures and to plan surgery and determine surgical resectability. CT can clearly show even very small bones as well as surrounding tissues such as muscle and blood vessels. This makes it invaluable in diagnosing and treating spinal problems and injuries to the hands, feet and other skeletal structures. CT images can also be used to measure bone mineral density for the detection of osteoporosis. In cases of trauma CT can quickly identify injuries to the liver, spleen, kidneys or other internal organs. CT can also play a significant role in the detection, diagnosis and treatment of vascular diseases that can lead to stroke, kidney failure or even death.
What to expect
A CT scan takes anywhere from around 10 min. to ½ hour to complete, although the actual scan time can be measured in seconds. During that time, you will be asked to lie very still on a table that moves in and out of a round opening called a "gantry". The ring inside the gantry contains an x-ray tube and receptors mounted on the opposite side. As the x-ray tube moves around you, the receptors on the opposite side measure the amount of x-ray that is absorbed. These measurements are fed into a computer that produces the images on a video screen for the radiologist to view. These images are then transferred onto x-ray film or read on a monitor at a computer workstation.
Since x-rays cannot penetrate metal you may be asked to remove any jewelry, glasses or clothing which has zippers or snaps, etc. You may be asked to put on a hospital gown or often we are able to leave you dressed in your own clothing simply by moving any metal out of the way. You may wish to wear a sweat suit or clothing without metal parts so that you don’t have to change into a gown.
How to Prepare for your CT Scan
When you are scheduled to have a CT scan you will be asked to remain NPO (no food) for at least 6 hours prior to your scheduled appointment. If your CT scan is scheduled for late in the day, we ask that you have a light breakfast, but NPO for 6 hours prior to your exam.
If you have medications that you normally take, you should go ahead and take them as prescribed. If you have to have food with your medication you could have a small amount of dry toast or crackers in addition to the clear liquids.
Depending on what part of your body is being scanned, you may be asked to drink a special liquid referred to as oral contrast media, gastrografin, or Redi-CAT. All patients who are having scans of their abdomen and/or pelvis are required to drink this special contrast. This contrast helps to outline your stomach and intestines so those normal structures can be clearly identified and to distinguish them from any abnormality. The oral contrast can be obtained in our facility prior to your exam so that you can drink it at home ahead of time.
Many, but not all, patients who have a CT scan will need to have a special type of iodine x-ray dye/contrast injected into their veins during the test. This IV contrast helps to highlight certain structures in your body or brain. It helps to visualize veins and arteries and certain tissues, as well as your urinary tract (kidneys, ureter, and bladder).
If you have an allergy to iodine or x-ray dye, please inform us or your doctor as soon as possible. If you are pregnant, diabetic or have known kidney problems, please inform us of that as well.
Once your test is complete
After your CT scan has been completed, you will be able to resume all of your normal activities. There should be no ill-side effects to keep you from doing this. You will be able to drive.
The only thing we recommend is that you drink plenty of liquids/water after your test is complete. This is so that the contrast dye can be quickly flushed from your body and you do not become dehydrated.