Find out how a CT scan can help to diagnose lung cancer and what happens during the test.
What it is
A CT scan uses x-rays to take detailed pictures of your body from different angles. A computer then puts them together to give a series of pictures.
CT (or CAT) stands for computerised (axial) tomography.
How you have it
You usually have a CT scan in the x-ray (radiology) department as an outpatient. A radiographer operates the scanner. The whole appointment can take up to an hour and a half.
Why you might have a CT scan
Doctors can use a CT scan to look for lung cancer. It can also show whether the cancer has spread outside the lung. The scan looks at your lungs and other parts of your chest. It can also look at your liver and adrenal glands. The adrenal glands are hormone producing glands on top of the kidneys.
Preparing for your CT scan
A couple of hours before your scan you might need to stop eating and drinking. Tell your doctor if this is a problem for you: for example, if you have diabetes.
Most people have a drink or an injection of contrast medium, or both. Contrast medium is a dye that helps body tissues show up more clearly on the scan.
Before you have the contrast medium, the radiographer asks if you have any medical conditions or allergies. Some people are allergic to the dye. They also check the results of your most recent blood test. This is to make sure your kidneys are working well and able to flush the contrast medium out of your body. You will need to have a blood test before the scan if you have not had one recently.
The radiographer explains how to drink the contrast. You usually drink a liquid slowly for about an hour before the scan.
Some people feel claustrophobic or closed in when they‘re having a scan. Tell the radiographers before your appointment if you think you’re likely to feel this way. They can take extra care to make sure you are comfortable and that you understand what’s going on. Your doctor can prescribe a medicine to relax you if you need it.
When you arrive at the scan department
The radiographer might ask you to change into a hospital gown. You’ll have to remove any jewellery and other metal objects, such as hair clips. Metal interferes with the images produced by the scanner.
In the scanning room
When you’re ready, the radiographer or assistant takes you into the scanning room. A CT scanning machine is large and shaped like a doughnut.
You might have an injection of contrast medium (a type of dye) through a small thin tube (cannula) in your arm. This can:
- make you feel hot and flushed for a minute or two
- give you a metallic taste in your mouth
- make you feel like you’re passing urine but you aren’t – this feeling is common and passes quickly
You can have a medicine to help you relax if you think you will feel claustrophobic during the scan.
Having the CT scan
You usually lie down on the machine couch on your back. Once you’re in the right position, the radiographer leaves the room. They can see you on a TV screen or through a window from the control room. You can talk to each other through an intercom.
The couch slowly slides backwards and forwards through the hole of the scanner. The machine takes pictures as you move through it.
The scan is painless but can be uncomfortable because you have to stay still. Tell your radiographers if you’re getting stiff and need to move.
During the scan
You’ll hear a whirring noise from the scanner.
The radiographer might ask you to hold your breath at times.
When the scan is over, the radiographer comes back into the room and lowers the couch so you can get up.
After your CT scan
You stay in the department for about 15 to 30 minutes if you had an injection of the dye. This is in case it makes you feel unwell, which is rare.
The radiographer removes the tube from the vein in your arm before you go home.
You should be able to go home or back to work. You can eat and drink normally.
You need someone to take you home if you had medicine to help you relax. You won’t be able to drive for the rest of the day as it could make you drowsy.
Getting your results
You should get your results within 1 or 2 weeks.
Waiting for results can make you anxious. Ask your doctor or nurse how long it will take to get them. Contact the doctor who arranged the test if you haven’t heard anything after a couple of weeks.
You might have contact details for a specialist nurse and you can contact them for information if you need to. It may help to talk to a close friend or relative about how you feel.
A CT scan is a safe test for most people but like all medical tests it has some possible risks. Your doctor and radiographer make sure the benefits of having the test outweigh these risks.
Rarely, people have an allergic reaction to the contrast medium. This most often starts with weakness, sweating and difficulty breathing. Tell your radiographer immediately if you feel unwell so they can give you medicine.
There is a risk that the contrast medium will leak outside the vein. This can cause swelling and pain in your arm but it’s rare.
Exposure to radiation during a CT scan can slightly increase your risk of developing cancer in the future. Talk to your doctor if this worries you.
Pregnant women should only have CT scans in emergencies. Contact the department as soon as you can before the scan if you are pregnant or think that you might be.