What is it?

A CT (computed tomography) scan uses X-rays to make detailed pictures of your body and the structures inside your body. A CT scan of the head can give your doctor information about your eyes, the bones of your face and nose, your inner ear, and your brain.

During the test, you will lie on a table that is attached to the CT scanner. The CT scanner is a large doughnut-shaped machine.

Why is this test done?

A CT scan of the head can help find the cause of symptoms that may mean you have a brain injury or bleeding inside your head. It can also find a tumour and damage caused by a stroke and help find the best treatment for the cause of a stroke.

How do you prepare for the test?

Talk to your doctor about all your health conditions before the test. For example, tell your doctor if:

• You are or might be pregnant.
• You are allergic to any medicines.
• You have diabetes.
• You take metformin.
• You are breastfeeding.
• You get nervous in confined spaces. You may need medicine to help you relax.

What happens during the test?

Before the test

• You may have to take off jewellery.
• You will take off all or most of your clothes and change into a gown. If you do leave some clothes on, make sure you take everything out of your pockets.
• You may have contrast material (dye) put into your arm through a tube called an I.V.

During the test

• You will lie on a table that is attached to the CT scanner.
• The table slides into the round opening of the scanner. The table will move during the scan. The scanner moves within the doughnut-shaped casing around your body.
• You will be asked to hold still during the scan. You may be asked to hold your breath for short periods.
• You may be alone in the scanning room. But a technologist will watch you through a window and talk with you during the test.

How long does the test take?

• The test will take about 30 to 60 minutes. Most of this time is spent getting ready for the scan. The actual test only takes a few minutes.

How does having a CT scan of the head and face feel?

The test will not cause pain, but some people feel nervous inside the CT scanner.

If a medicine to help you relax (sedative) or dye is used, you may feel a quick sting or pinch when the IV is started. The dye may make you feel warm and flushed and give you a metallic taste in your mouth. Some people feel sick to their stomach or get a headache. Tell the technologist or your doctor how you are feeling.

What else should you know about the test?

• A CT scan does not hurt.
• If a dye is used, you may feel a quick sting or pinch when the I.V. is started. The dye may make you feel warm and flushed and give you a metallic taste in your mouth. Some people feel sick to their stomach or get a headache.
• If you breastfeed and are concerned about whether the dye used in this test is safe, talk to your doctor. Most experts believe that very little dye passes into breast milk and even less is passed on to the baby. But if you prefer, you can store some of your breast milk ahead of time and use it for a day or two after the test.
• There is a small chance of getting cancer from some types of CT scans. The risk is higher in children, young adults, and people who have many radiation tests. If you are concerned about this risk, talk to your doctor about the benefits and risks of a CT scan and confirm that the test is needed.

What happens after the test?

• You will probably be able to go home right away.
• You can go back to your usual activities right away.
• Drink plenty of fluids for 24 hours after the test if dye was used, unless your doctor tells you not to.