CT Scan (General)
(Computed Tomography Scan; Computed Axial Tomography; CAT Scan)
A CT scan uses x-ray technology to take multiple views of the inside of the body. Compared to regular x-rays, a CT scan can take clearer and more detailed images of organs, bone, soft tissue, blood vessels, and other parts of the body.
CT Scan of the Head
Reasons for test
Some of the primary uses for CT scans include:
- Looking for bleeding inside the body, especially the in the skull.
- Studying the chest and abdomen
- Determining the size and location of a tumor
- Diagnosing skeletal problems
- Diagnosing blood vessel diseases
- Planning radiation treatments for cancer
- Guiding biopsies and other tests
- Planning surgery
- Identifying injuries from trauma
Complications are rare, but no procedure is completely free of risk. If you are planning to have a CT scan, your doctor will review a list of possible complications. These may include:
- Allergic reaction to contrast material
- Damage to the kidney from contrast material
Factors that may increase the risk of complications include:
- Allergies (if you are given a contrast dye during the test)
- Kidney problems (if you are given a contrast dye during the test)
You are exposed to some radiation during a CT scan. Radiation exposure can increase your lifetime risk of cancer. This risk increases the more times you are exposed to radiation. Radiation exposure is more concerning for pregnant women and children. CT scans are usually not recommended for pregnant women.
Be sure to discuss these risks with your doctor before the test.
What to Expect
Prior to Test
Before the test, your doctor will likely ask about:
- Your medical history
- Medications you take
- Whether you are pregnant or trying to get pregnant
- Before your test, follow your doctor’s instructions regarding any changes to your medications or diet.
At the healthcare facility:
- A healthcare professional will explain the test and answer any questions you may have.
- You will remove your clothes and put on a gown or robe.
- You will remove all jewelry, hair clips, dentures, and other objects that could show on the x-rays and make the images hard to read.
- If your CT scan includes oral contrast material, you will need to drink the contrast material at this time.
Description of the Test
You will lie (usually on your back) on a movable bed. The bed will slide into the donut-shaped CT scanner. Depending on the type of scan, an IV line may be placed in your hand or arm. A saline solution and contrast material may be injected into your vein during the test. The technologist will leave the room. You will be given directions using an intercom. The machine will take a series of pictures of the area of your body that is being studied. Your bed may move slightly between pictures.
You will need to wait for the technician to review your images. In some cases, more images will need to be taken.
Will It Hurt?
You may feel warm and flushed if contrast material is injected into your vein. Otherwise, you should feel no pain.
Call Your Doctor
After the test, call your doctor if any of the following occur:
- Symptoms of allergic reaction, such as hives, itching, nausea, swollen or itchy eyes, tight throat, or difficulty breathing
- Any other concerns
In case of an emergency, call for emergency medical services right away.
Radiological Society of North America
US Food and Drug Administration
Canadian Association of Radiologists
Canadian Radiation Protection Association
Computed tomography (CT)—body. Radiological Society of North America website. Available at: http://www.radiologyinfo.org/en/info.cfm?pg=bodyct&bhcp=1. Updated September 23, 2014. Accessed January 26, 2015.
Radiation-emitting products: computed tomography (CT). US Food and Drug Administration website. Available at: http://www.fda.gov/Radiation-EmittingProducts/RadiationEmittingProductsandProcedures/MedicalImaging/MedicalX-Rays/ucm115317.htm. Updated January 23, 2014. Accessed January 26, 2015.
Last reviewed January 2015 by Michael Woods, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.