Recent Blog Articles

Save the trees, prevent the sneeze

Drug recalls are common

Easy ways to shop for healthful, cost-conscious foods

Prostate cancer in transgender women

Why eat lower on the seafood chain?

Can long COVID affect the gut?

When replenishing fluids, does milk beat water?

Safe, joyful movement for people of all weights

Slowing down racing thoughts

Are women turning to cannabis for menopause symptom relief?
Computed Tomography (CT)
What Is It?
CT scans are pictures taken by a specialized x-ray machine. The machine circles your body and scans an area from every angle within that circle. The machine measures how much the x-ray beams change as they pass through your body. It then relays that information to a computer, which generates a collection of black-and-white pictures, each showing a slightly different "slice" or cross-section of your internal organs.
Because these "slices" are spaced only about a quarter-inch apart, they give a very good representation of your internal organs and other structures. Doctors use CT scans to evaluate all major parts of the body, including the abdomen, back, chest, and head.
You can have a CT scan in an outpatient facility or in a hospital. The procedure is painless and takes about 20 minutes, but can be longer or shorter depending on the area of the body being scanned.
What It's Used For
CT can reveal abnormal masses that may be cancerous tumors. CT scans show the size and shape of the tumor, its precise location in the body, and whether the tumor is solid or hollow. Sometimes, a CT scan can tell the difference between a noncancerous and cancerous tumor, although a biopsy or other test is needed to make the final diagnosis. In a biopsy, a small piece of tissue is removed to be examined in a laboratory. During a CT-guided biopsy, the physician will use the CT scan as a guide as he or she inserts the needle into the right location to remove a sample of the tumor.
In addition to detecting cancer, CT scans have many other uses. They can show abscesses and other infections, strokes, head injuries and bleeding inside the skull, as well as a variety of other medical conditions.
For obese patients, CT scanning may be a more useful diagnostic tool than ultrasound, because large amounts of body fat can interfere with ultrasound waves, producing poor images.
Preparation
CT scanning usually does not require any special preparation. Remove jewelry in the area being scanned. If you are a woman and there is any chance that you may be pregnant, tell your doctor before your scan.
You may need to drink a liquid dye to make organs or blood vessels stand out more clearly on the CT scan. Sometimes, this dye, called a "contrast medium," is injected into your vein. Tell your doctor if you have ever had an allergic reaction to this sort of dye or if you have any allergies to medicines. If you take a diabetes medication called metformin (Glucophage), ask your doctor if you should stop taking it 48 hours before your test, because it may interact with the contrast dye.
How It's Done
You will lie down on a special scanning table. The scanner rotates 360° around you. The scanning table also may be moved.
Follow-Up
A radiologist (a doctor who specializes in imaging) reads and interprets your CT images. The personnel at the CT scan facility will tell you when to check with your doctor for the results of your scanning.
Risks
Although CT scanning requires a slightly higher amount of X-ray exposure than conventional X-rays, it gives images that are much clearer.
When To Call A Professional
If you received contrast dye by an injection, and the injection site becomes red or painful, call your doctor.
Additional Info
National Library of Medicine (NLM)
http://www.nlm.nih.gov/
American College of Radiology
http://www.acr.org/
Disclaimer:
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.
No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
Free Healthbeat Signup
Get the latest in health news delivered to your inbox!