Computed Tomography (CT) Scan

What is a CT scan?

A CT (computed tomography) scan is a test that uses computers and X-rays. It takes detailed, 3D images of the inside of the body.

CT scans can:

• Show detailed images of bones, organs, and tissues
• Diagnose a tumor
• Provide information about the stage of cancer
• Guide procedures like a biopsy

The appointment may only take 10-20 minutes.

The scan itself only lasts a few seconds. But it may be repeated if your child needs a test with a contrast agent.  

Contrast agents are clear liquids that may be swallowed or injected.

• If swallowed, the contrast agent might smell or taste funny.
• If injected through an IV, the liquid may feel warm as it goes into the vein. 

What to expect at a CT scan appointment

Each center has its own procedures. But this general advice can help most families.

Preparing for the scan: Be sure your child dresses in loose, comfortable clothing. Avoid clothing and accessories that contain metal. That includes:

• Belts
• Zippers
• Snaps
• Buttons
• Hair accessories
• Watch
• Jewelry
• A non-permanent retainer 
• Glasses (especially for a head CT scan)

Be sure to let the care team know if your child:

• Is allergic to contrast agents or iodine
• Might be pregnant
• Is uncomfortable in small spaces
• Has special behavior needs 
• Has diabetes or kidney problems

Most centers will allow your child to bring a comfort item, like a stuffed animal or a blanket. Ask your care team if your child can bring a comfort item to the appointment.

• Checking-in/registering: Be sure to arrive a few minutes early. You’ll check-in at the registration desk with your child. Then you’ll wait until your child’s name is called. Your child may need to change into a hospital gown.
• Meeting the CT technologist: A CT technologist will escort you into a special area that houses the CT scanner. A child life specialist may also be there to help answer questions. 

• During the scan: The machine is shaped like a large donut with a special bed, also called a table, in the middle. The CT technologist will position your child on the table. This table can move so your child is in the right location for the scan. The technologist may put towels around your child’s head. A small, soft belt over the forehead to help your child to stay still. The CT technologist will move to an area close by and will be able to see, hear, and talk to your child during the procedure.  
• What your child will see and hear: When the scan starts, your child will see the red lines of the camera. The CT machine will make a loud noise, such as a “clunk” when the scanner starts and a “whir” or “whoosh” as the camera. The camera will not touch your child. Your child will not feel anything as the detectors collect data for the pictures. 
  
• After the test: The technologist will unfasten safety belts and disconnect the IV if one was used. Then your child may get off the table and leave the area. 
• Test results: A physician called a radiologist will study the images. Your child’s doctor will get an official report with the results. The report may take a few days.
• Conference with the physician: The doctor will discuss the results of the CT with you. 
• Follow-up: Your child may need follow-up exams or tests. If they do, your child’s doctor will explain the tests to you. 

CT scans and sedation

Your child will only be sedated for a CT scan if they need it to stay still during the test.

Images can blur if your child doesn’t stay still. So, remaining still during the test is important. It can help if you tell your child to pretend to be a statue. Or they can pretend to be asleep. 

Depending on your child’s age, they may be asked to hold their breath for a moment.

CT scan safety

If the CT scan is medically necessary, experts say the benefits outweigh the small, long-term risk of radiation exposure.

Benefits

The scans give doctors a wealth of information to help diagnose and treat cancer.

CT images of organs, bones, tissue, and blood vessels are more detailed than X-rays . These images can be reformatted in multiple planes. They can produce 3D images. 

Risks

CT scans use a small amount of radiation. The radiation will be adjusted according to your child’s age and size. Most centers work to reduce the dose of radiation.

Radiation exposure from CT scans affects children differently than adults. Children are more sensitive to radiation. This is because they are still growing. Also, they have a longer life expectancy than adults. That means there is more time for radiation-related side effects, including the very low risk of cancer, to develop.  

The lifetime risk of cancer from a single CT is small. It’s about 1 case for every 10,000 scans in children, according to the National Institutes of Health. 

The risk increases when multiple CTs are performed.

Here are some questions to ask your child’s care team if you are concerned about radiation exposure:

1. Why is the test needed?
2. Will the results change the treatment decisions?
3. Is there an alternative test that doesn’t involve radiation?

If you have any questions about CT safety, talk with your child’s care team.