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What is a CT scan? A "CT" or "CAT" scan is the term used to
describe a radiologic test known as "computerized tomography." The CT scanner is
a doughnut-shaped machine that takes X-ray pictures of cross-sections of your body, called
"slices." CAT is an acronym for "computerized axial tomography." CAT has been replaced with a new acronym, CT, that simply stands for "computed tomography." Tomography is the process of making an image of a plane(slice) through the body. A CAT scan or a CT scan is a procedure that uses x rays, radiation detectors, and computers to produce images of planes through the body. Rather than using conventional x-ray film to intercept and record information in the x-ray beam that passes through the body, CT scanners use radiation detectors. The x-ray tube and the radiation detectors are positioned on opposite sides of the body. The x-ray tube and detectors rotate around the body. As this is happening, the detectors accumulate information about how much of the x-ray beam passes through the body. This information from the detectors is fed into a computer that performs millions of calculations and determines what must have been in the path of the x-ray beam to absorb x rays the way they were absorbed as they passed through the body. The computer then creates an image that represents a slice (plane) through the body traversed by the x-ray beam. Conventional x-ray procedures give images such as you would see in looking at a whole hard-boiled egg from the side. CT scans let the radiologists see planes through the egg such as you would see if you put the egg through an egg slicer and then removed each slice and looked down on the top of the egg. As you peel off each slice, you begin to see the yolk getting larger with each slice. Once you pass the middle of the yolk, it begins to get smaller with each slice removed. By creating a series of CT images (slices) down the body, the radiologist can look at each image and get an accurate indication of position, size, and density of objects within the body. Our computers can take all of the slices (images of planes through
the body) and assemble them into a 3-D image that can be rotated and looked at from
various directions. CT scanners are very important diagnostic tools in modern radiology. Is it uncomfortable? Is it dangerous? The test itself is completely painless. You will be asked to lie quietly on the CT scanner's "patient couch" during the study. Depending on the type of study being done, you may be injected with contrast material. This part of the procedure may be uncomfortable. Because contrast agents contain iodine, which causes an allergic reaction in some individuals be sure to tell the technologist, nurse or radiologist if you have had an allergic reaction to these agents before, or if you have any other allergies. You may have been given contrast material earlier as part of a CT scan, a kidney x-ray (also called an IVP), or a heart or blood vessel catheterization (also called an angiogram). CT scanners use x-rays. For your safety, the amount of radiation is kept to an absolute minimum and our equipment is kept in top shape. Because x-rays can harm a developing fetus, however, be sure to tell your doctor if you are, or think you may be, pregnant before preparing for the CT exam. Even if you haven't told your doctor, be certain to tell the CT scan technologist who prepares you for the study. On the day of your CT scan, please do not eat solid food for four
hours prior to your CT appointment. You may, however, have clear liquids (black
coffee/tea, broth, clear soups, or juice) during this time in moderate amounts.
Restricting solid foods in order to avoid stomach distress is a common safety precaution
before many medical procedures. At the CT scan suite Plan to arrive at the CT scan suite at least 15 minutes before your scheduled appointment. This will allow the necessary time to prepare your paperwork. You will be asked to fill out a brief questionnaire about your medical history, medications and allergies, and insurance. If you are to be given a contrast dye, you doctor may have you take a blood test BEFORE the CAT scan, to ensure that your kidneys are working well. Unless instructed otherwise, you should empty your bladder, so that
you don't have to go to the restroom during the test. What happens during the scan? The technologist will bring you into the CT scan room where you will
lie down on the patient couch (usually on your back). You should get comfortable because
it is very important that you not move during the test. CT examinations differ depending
on your medical problem and the part of your body being studied. The radiologist will plan
an examination that is best suited for you. As part of your test, before or during the study, you may have an IV started or be given an injection (by a nurse, technologist or doctor) of a contrast agent. This allows the radiologist to obtain clearer image. Should you have any discomfort during the test or after the injection, tell the technologist. The dye may cause a brief feeling of heat or flushing. THis should only last a minute or two. Report ANY feelings of nausea, vomiting, dizziness, headaches, sneezing or hives. THESE SIDE EFFECTS ARE RARE. You will be alone in the room, but the technicians and medical staff will be observing you, and will be able to hear you and talk to you during the test. How long does a CT scan take? Each examination is tailored to individual requirements, so don't be
alarmed if your exam is different from one you've had before, or if some additional
pictures are taken after the first series is completed. From start to finish, the
picture-taking part of the test usually lasts only 10 to 15 minutes. What happens after the scan? Once the CT staff are sure
that enough information has been collected, any IV will be removed, and you may
leave and go about your normal activities without restriction. When do I get the results? Your exam will be reviewed by radiologists who specialize in this
type of imaging. Results are then available to your doctor. A formal written report is
then sent to the requesting doctor. Contact your doctor if you want to know about the
results. What if I have other questions? If you have any questions about your CT scan, please ask any of our
personnel (physicians, nurses, technologists, receptionists). We will try our best to
explain the procedure clearly and to make your visit to the CT suite as comfortable and
speedy as possible. |