23rd January 2026
Lung Scan - Types, Process, Duration, Risks
What is a Lung Scan?
A lung scan is a type of nuclear scanning test. It uses a special camera to take pictures of the lungs after a radioactive marker has been placed in the body.
It is most commonly used to detect pulmonary embolism. This is a blood clot that prevents normal blood flow in the lungs.
There are two types of lung scans that are usually done together. They are:
Airway Scan
You inhale a radioactive tracer gas or mist. The images from this scan can show areas of the lungs that are not getting enough air or are holding too much air.
Perfusion Scan
A radioactive tracer is injected into a vein in your arm. It travels through your blood and into your lungs. The images from this scan can show areas of your lungs that are not getting enough blood.
If both scans are done, the test is called a V/Q scan. Usually, the ventilation scan is done first.
In most cases, if your lungs are working properly, both scans will show that the parts of your lungs that are getting air are also getting blood. If the results of the two scans don't match, the differences can help your doctor diagnose a problem with your lungs.
The results of the lung scan can help your doctor understand how likely you are to have a blood clot in your lung. If you are likely to have a blood clot, your doctor may order more tests. If the chance is high, your doctor may give you medicine to treat the clot.
Why is a Lung Scan Performed?
A lung scan is done to:
- Find a blood clot that is blocking normal blood flow to part of the lung.
- Look at the flow of blood or air through the lungs.
- See which parts of the lungs are working and which are damaged. This is often done before surgery to remove parts of the lung.
How to Prepare for a Lung Scan
If you are breastfeeding, express enough milk before the test. The radioactive marker used in this test may get into your milk and not be good for your baby.
How is a Lung Scan Performed?
During the scan, the camera may move to take pictures from different angles.
Ventilation scan
- A mask will be placed over your mouth and nose, or you may have a nose clip on your nose and a tube in your mouth that you use to breathe. You will take a deep breath and hold it.
- The camera will take pictures as the marker moves through your lungs.
- You may be asked to inhale and exhale the gas through your mouth for a few minutes and then hold your breath for short periods (about 10 seconds). You may need to change positions so that your lungs can be seen from different angles.
- The gas or mist will then clear from your lungs as you breathe.
Perfusion Scan
- A small amount of the tracer will be injected into your arm.
- The camera will take pictures as the tracer moves through the blood vessels in your lungs.
How Long Does a Lung Scan Take?
The two scans are usually done together and take about an hour. The ventilation scan takes about 15 to 30 minutes, and the perfusion scan takes about 5 to 10 minutes. The scan can be done on its own.
What Are the Risks of a Lung Scan?
- Allergic reactions to the radioactive tracer are very rare.
- Whenever you are exposed to radiation, there is a small chance of damage to cells or tissues. This is the case even with the low-level radioactivity indicator used for this test. However, the chance of damage is very low compared to the benefits of the test.
What Happens After a Lung Scan?
- Most of the tracer will leave your body through your urine or stool within a day.
- After the test, drink plenty of fluids for the next 24 hours to help flush the tracer from your body.
- The radioactive tracer used in this test may get into your breast milk. Do not breastfeed your baby for 1 or 2 days after this test. During this time, you can give your baby breast milk that you stored before the test, or you can give formula.
- Some people experience soreness or swelling at the injection site. A moist, warm compress on the arm may help.
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