CT scan or Computerized Tomography — also just called CT — combines a series of X-ray views taken from many different angles and computer processing to create cross-sectional images of the bones and soft tissues inside your body.
The resulting images can be compared to looking down at single slices of bread from a loaf. Your doctor will be able to look at each of these slices individually or perform additional visualization to view your body from different angles. In some cases, CT images can be combined to create 3-D images. CT scan images can provide much more information than do plain X-rays.
A CT scan has many uses, but is particularly well suited to quickly examine people who may have internal injuries from car accidents or other types of trauma. A CT scan can be used to visualize nearly all parts of the body.
Your doctor may recommend a CT scan to help:
- Diagnose muscle and bone disorders, such as bone tumors and fractures
- Pinpoint the location of a tumor, infection or blood clot
- Guide procedures such as surgery, biopsy and radiation therapy
- Detect and monitor diseases and conditions such as cancer, heart disease, lung nodules and liver masses
- Detect internal injuries and internal bleeding
Preparing for a CT Scan
Depending on which part of your body is being scanned, you may be asked to:
- Take off some or all of your clothing and wear a hospital gown
- Remove metal objects, such as a belt, jewelry, dentures and eyeglasses, which might interfere with image results
- Refrain from eating or drinking for a few hours before your scan
Contrast material
A special dye called a contrast material is needed for some CT scans, to help highlight the areas of your body being examined. The contrast material blocks X-rays and appears white on images, which can help emphasize blood vessels, intestines or other structures.
Contrast material might be given to you:
- By mouth. If your esophagus or stomach is being scanned, you may need to swallow a liquid that contains contrast material. This drink may taste unpleasant.
- By injection. Contrast agents can be injected through a vein in your arm to help your gallbladder, urinary tract, liver or blood vessels stand out on the images. You may experience a feeling of warmth during the injection or a metallic taste in your mouth.
- By enema. A contrast material may be inserted in your rectum to help visualize your intestines. This procedure can make you feel bloated and uncomfortable.
During the CT scan
CT scanners are shaped like a large doughnut standing on its side. You lie on a narrow, motorized table that slides through the opening into a tunnel. Straps and pillows may be used to help you stay in position. During a head scan, the table may be fitted with a special cradle that holds your head still.
While the table moves you into the scanner, detectors and the X-ray tube rotate around you. Each rotation yields several images of thin slices of your body. You may hear buzzing, clicking and whirring noises.
A technologist in a separate room can see and hear you. You will be able to communicate with the technologist via intercom. The technologist may ask you to hold your breath at certain points to avoid blurring the images.
After the CT scan
After the exam you can return to your normal routine. If you were given a contrast material, you may receive special instructions. In some cases, you may be asked to wait for a short time before leaving to ensure that you feel well after the exam. After the scan, you’ll likely be told to drink lots of fluids to help your kidneys remove the contrast material from your body.