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Key Points
- A CT scan is a medical imaging procedure that uses X-rays and a computer to create detailed 3-D images of the body's bones and tissues.
- CT scans are more detailed than standard X-rays and are used to diagnose and monitor conditions like tumors, infections, and internal bleeding, as well as to guide medical procedures and evaluate treatment effectiveness.
- The preparation for a CT scan is minimal, possibly including fasting and removing metal objects, and contrast material may be used to enhance the visibility of internal structures.
- While generally safe, CT scans do carry some risks, such as radiation exposure, allergic reactions to contrast material, and potential kidney damage in patients with pre-existing kidney conditions.
- The CT scan procedure is typically quick, but the entire process may take up to two hours, after which patients can usually return to their normal activities.
A CT scan (short for “computed tomography” and also called a “CAT scan”) is a radiology imaging test that helps healthcare providers find evidence of disease inside the body, as well as diagnose injuries. According to the Cleveland Clinic, a CT scan uses a series of X-rays and a specialized computer to see detailed snapshots of your bones and soft tissues, one micro-layer at a time. A CT scan is painless and noninvasive, but there are some risks you should consider, according to the Cleveland Clinic.
What Is a CT Scan?
A CT scan is similar to an X-ray in that it can show different views and structures inside your body. Some people may confuse a CT scan and an MRI scan, both are common imaging techniques, but an MRI uses magnetic energy instead of radiation like the cat scan. CT scans are more detailed than an average X-ray—taking anywhere from a couple dozen to hundreds of X-ray images, according to the Cleveland Clinic. These X-rays are layered and computerized to give doctors a 3-D view of your body.
A CT scan allows a radiologist to see things an X-ray can’t show, like certain body structures that overlap or appear clear on an X-ray.
Why It’s a CT Scan Done?
A CT scan is done to get highly detailed images of the inside of the body—commonly used to diagnose and monitor different conditions, including:
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Tumors
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Infections
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Injuries
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Internal bleeding
Additionally, CT scans are useful for guiding medical procedures, such as biopsies and surgeries, and for evaluating the effectiveness of ongoing treatments.
How Do You Prepare Before a CT Scan?
There are very few preparations needed for a CT scan, and your doctor will be able to give you specific instructions if there are any. According to the Mayo Clinic, women who are pregnant or breastfeeding should inform the medical staff before a CT scan. Additionally, they note that you should fast from food and drink for a few hours before your scan.
If you are scheduled for a CT scan, consider the following steps from the Mayo Clinic:
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Arrive early so you have time to check in
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You may or may not be asked to change into a hospital gown
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Remove metal objects (such as a belt or jewelry). You should also remove your dentures and eyeglasses, because they may interfere with image results
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Drink only clear liquids (like water, juice, or tea) in the two hours leading up to your appointment (this is especially important for abdominal CT scans)
Contrast Material
Contrast material (also known as contrast dye) is an iodinated contrast substance used in medical imaging to enhance the visibility of internal structures or organs. Barium is another type of contrast that is used for computed tomography (CAT scans). The iodinated contrast material helps to highlight specific areas inside the body — allowing doctors to get a better view. This is particularly useful in identifying tumors, problems with blood vessels, and areas of inflammation or infection, according to the Mayo Clinic.
CT scanners may require contrast material to improve the visualization of blood vessels, organs, tumors, and other abnormalities that may not be clearly visible with standard imaging techniques.
Contrast dye can be given in a few different ways, according to the Mayo Clinic, including:
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By drinking a barium solution
- Through an intravenous line (IV) placed in your arm or hand
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By enema (commonly used for abdominal CT scans)
CT Scan Risks
A CT scan does use radiation to gather imaging, so there are some risks involved. According to the Mayo Clinic, these risks include:
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Radiation exposure, which carries a small risk of potentially harmful effects, particularly with repeated scans.
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Allergic reactions to iodinated contrast or barium, which can range from mild to severe.
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Risk of kidney damage in patients with pre-existing kidney conditions due to the use of contrast material, including barium and iodinated contrast given through intravenous lines.
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Potential for adverse reactions to sedatives, anesthesia, barium, or iodinated contrast used during the procedure.
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Rare risk of developing cancer from the cumulative effects of radiation exposure over time, especially in young children and individuals with high cumulative radiation exposure.
What to Expect During a CT Scan?
CT scans are fairly common, according to the Cleveland Clinic. But if you’ve never had one before, you may be wondering what to expect. Here are some insights from the Cleveland Clinic:
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Preparation: You may be asked to avoid eating or drinking for a few hours before the scan, especially if iodinated contrast or barium will be used. It's important to follow any specific instructions provided by your healthcare provider.
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Clothing: You may be required to change into a hospital gown, as clothing with metal components can interfere with the CT scan.
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Contrast material: If iodinated contrast material is needed for the scan, it may be administered orally, intravenously, or through other routes.
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Positioning: You will be positioned on a movable table that slides into the CT scanner, which resembles a large, donut-shaped machine. It's important to remain still during the scan to ensure clear images.
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Monitoring: A technologist will operate the CT scanner from an adjacent room and will be able to communicate with you through an intercom. They will monitor the scan to ensure that the images are high quality.
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Duration: A CT scan typically takes only a few minutes, but the entire process, including preparation and post-scan observation, may take one to two hours or more, depending on the area that is being scanned.
After a CT Scan
According to the Mayo Clinic, after your CT scan, you may be able to resume normal activities unless you were given a sedative or anesthesia. If this is the case, you will need some time to recover before leaving and will need someone to drive you home.
Lab Tests Near Me
A CT scan usually needs to be ordered by a physician. If you need a CT scan, you can find a provider who can order one for you using Solv.
Frequently asked questions
What should you not do before a CT scan?
Before getting a CT scan, the Mayo Clinic notes that you should avoid eating or drinking for a few hours, especially if iodinated contrast is used during your scan. Additionally, it's important to inform the technician about any allergies, pre-existing medical conditions, or medications being taken — these factors can affect the scan or the use of contrast material. It is also important to follow any specific instructions provided by the healthcare provider to ensure the success and safety of the procedure.
Can you eat or drink before a CT scan?
The Mayo Clinic advises that you should not eat or drink for a few hours before your CT scan. This is especially important if you are getting contrast dye during your scan or if you are having an abdominal CT scan.
Can you wear deodorant for a CT scan?
According to South Jersey Radiology, some personal hygiene and makeup products contain small traces of metal, which can react badly inside the CT scanner. They recommend that you avoid wearing deodorant, mascara, makeup, nail polish, or heavy creams during your CT scan.
How long does a CT scan take?
A typical CT scan without intravenous contrast, can take about 10 to 20 minutes, according to Mount Sinai. They also note that if IV contrast is used, it can take about 30 to 60 minutes. Highly detailed CT scans can take even longer. Your technician will be able to advise how long your scan may take.
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