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Computed Tomography (CT) Scan

What is a CT scan?

A CT (computed tomography) scan is an imaging test that uses computers and X-rays. The scan takes detailed, 3D images of the inside of the body. CT scans often focus on a certain area of the body such as the head, chest, or abdomen. CAT scan is another term used for this type of imaging test.

CT scans can be used to:

  • Take pictures of bones, organs, tissues, and blood vessels
  • Guide procedures like a biopsy
  • Detect a tumor
  • Provide information about the stage of cancer
  • Detect problems such as blood clots or bleeding

Your health care provider may order a CT scan with contrast. Contrast agents are clear liquids that are swallowed or injected into a vein by IV. The contrast material can highlight certain areas of the body on the scan. Sometimes a contrast agent is needed to make the images even more clear and detailed.

How to prepare for a CT scan

Each center has its own procedures. Talk to your care team about what to expect and how to prepare for your appointment.

Talk to your child about staying still: It is important that your child knows what to expect and understands they will need to lie still during the test. A child life specialist or other care team member might help your child with relaxation techniques.

CT scans, or CAT scans, are imaging tests used to take pictures of the body. Watch this video to learn how CT scans are used to diagnose cancer and plan treatments.

Comfort items: 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.

Eating and drinking before the scan: Follow your care team’s instructions for what your child can eat or drink before the scan. If your child is going to have general anesthesia, they must not eat or drink for several hours before the test. You will get more specific instructions from your child’s care team.

Checking-in for your appointment: Be sure to arrive a few minutes early. Check in at the registration desk with your child. Then you’ll wait until your child’s name is called.

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

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

What to wear: 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)

 In some cases, your child may need to change into a hospital gown.

CT Scans with Anesthesia

Your child must hold still during the CT scan so that images do not blur. In some cases, your child may get sedation medicines or general anesthesia for a CT scan.

  • Sedation uses medicines that cause relaxation or sleepiness.
  • General anesthesia causes a complete loss of consciousness, like a very deep sleep.

Anesthesia is safe for most patients. But health care providers try to limit the use of general anesthesia in children. Talk to your care team about options for your child. There might be other ways to help your child stay still during imaging tests.


What to expect during a CT scan 

CT technologist administers contrast to a pediatric cancer patient with her mom nearby.

A CT scan uses a computer and X-rays to take detailed pictures inside the body.

The scan itself only lasts a few seconds. But it may be repeated if your child needs a test with a contrast agent.  The appointment may only take 10–20 minutes. A longer time will be needed if contrast or general anesthesia is used.

  • When it is time for the scan, a medical professional called a radiology  technologist will take you and your child into a special area that houses the CT scanner. A child life specialist may also be there to help answer questions. 
  • The CT scanner is a big machine shaped like a large donut. It has a special bed, also called a table, in the middle.  This table can move so your child is in the right location for the scan. 
  • The technologist will position your child on the table. 
  • The technologist may put towels, cushions, or safety belts around your child to keep them in the correct position. 
  • The  technologist will move to an area close by during the test. They will be able to see, hear, and talk to your child during the scan.  Each pediatric center has different policies, but usually a parent is allowed to be in the adjoining room with the technologist.
  • The CT scan is painless, but some children may feel anxious or have trouble staying still. 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.

What  your child will see and hear: The table will move slowly into the scanner until your child is in the correct position. When the scan starts, your child will see the red lines of the camera. The CT machine will make noises, such as a “clunk” when the scanner starts and a “whir” or “whoosh” as the camera works. The machine will turn around your child so it can take pictures from different angles. The camera will not touch your child. Your child will not feel anything during the scan. 

After the CT scan

When the scan is complete, 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. 

Your child can resume normal activities if they did not have sedation or general anesthesia. If your child did receive these medicines, they will need to recover first.

 A doctor called a radiologist will study the images and prepare a report of the results for your child’s care team. The report may take a few days.

Your health care provider will discuss the results of the CT scan with you. 

Possible risks of CT scans

CT scans use a small amount of radiation. Radiation exposure may increase the risk for cancer. However, this risk is small.

Children are more sensitive to radiation because they are still growing and have longer life expectancy. The risks associated with radiation may increase if your child has repeated or prolonged exposure to radiation.

Your care team will take steps to keep the dose of radiation as low as possible. The radiation dose used in CT scans is adjusted for your child’s age and size.

Side effects of contrast

If a contrast agent is used for the CT scan, your child might have minor side effects. These include:

  • Headache
  • Feeling dizzy
  • Feeling warm or flushed
  • Strange taste in the mouth
  • Nausea or vomiting
  • Allergic reaction

If you have any questions about CT side effects or safety, talk with your child’s care team. Learn more about types of imaging tests.

Questions to ask your care team

  • Why is the test needed?
  • How will the results be used?
  • Does my child need to stop eating or drinking before the test?
  • How can I help my child stay still during the test?
  • Will a contrast agent be used?
  • Will my child get sedation medicines or general anesthesia?
  • What are the risks or side effects?
  • When and how will we get the results?

Key points about CT scans

  • A CT scan is an imaging test that takes detailed pictures inside the body.
  • A contrast agent may be used to highlight certain parts of the body on the scan.
  • CT scans are generally safe and painless.
  • Your child will have to stay very still for the scan so that the images will be clear.
  • Follow your care team’s instructions on how to prepare for the CT scan.

Reviewed: October 2023