What is it?

A CT (computed tomography) scan uses X-rays to make detailed pictures of your body and structures inside your body. A CT scan of the chest can give your doctor information about your lungs, your heart, and other structures in your chest.

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 chest can help find problems such as infection, lung cancer, blocked blood flow in the lung (pulmonary embolism), and other lung problems. It also can be used to see if cancer has spread into the chest from another area of the body.

A low-dose CT scan is a different type of chest CT scan. It may be used as a lung cancer screening test for some smokers. Your age and how much you've smoked help your doctor decide if this would be a helpful test for you. This type of CT scan uses less radiation than a regular chest CT scan.

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?

• You will lie on a table that is attached to the CT scanner.
• The table will slide into the round opening of the scanner. The table will move during the scan. The scanner moves inside 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 be watching you through a window and talking with you during the test.

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.

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.

What happens after the test?

• Drink plenty of fluids for 24 hours after the test if dye was used, unless your doctor tells you not to.