VQ lung scan

A VQ scan looks at the air supply (ventilation) and blood supply (perfusion) to your lungs. It helps us to diagnose lung conditions. It is most commonly used to detect the presence of blood clots in the lungs (pulmonary embolism, PE).

VQ scans are done in the nuclear medicine department, using a gamma camera.

Preparing for a VQ scan

There is no special preparation for this scan. You can eat, drink and take any medicines as normal.

You should be prepared to be at the hospital for up to 1 hour.

If you are breastfeeding, contact the department before your appointment so we can give you more information before you come for your scan.

During a VQ scan

You will meet our team of technologists, or radiographers and they will explain the procedure to you. You can ask any questions about the scan.

You will be asked to remove any metal items, such as mobile phones or wallets, from around your chest area.

For the ventilation part of the scan, you will be asked to breathe in a slightly radioactive gas through a mouthpiece or mask.

For the perfusion part of the scan, you will be given an injection of a tracer. The tracer is a radioactive fluid, that is absorbed by the blood and travels to your lungs. The tracer helps us to see your images clearly.

We take a 3D scan (SPECT/CT) of the air and blood supply to your lungs. You will be asked to lie very still on the camera bed, with your arms above your head for 20 to 30 minutes. You can breathe normally during the scan. The camera will rotate around your chest, but will not touch you.

Pregnancy and breastfeeding

As the scan involves an injection of a radioactive tracer, you must tell us if you are, or think that you might be, pregnant, or if you are breastfeeding. If possible, please tell us as soon as you receive your appointment.

It is OK for you to have a lung scan if you are pregnant, but if you are, or think you might be pregnant, you must tell us as soon as possible.

For all nuclear medicine scans we check your pregnancy status with you before using any radioactive tracer.

Pain during a VQ scan

The injection during the perfusion part is similar to a blood test and there is no pain associated with the tracer.

After a VQ scan

There are no side effects from this scan and you can carry on with your normal activities.

After the scan you will still have some radioactivity left in your body. For the rest of the day, avoid any non-essential prolonged contact with children, and anyone who might be pregnant. This is to reduce the amount of unnecessary radiation to babies and children.

Risks of a VQ scan

We feel that the potential benefits of the test outweigh the very small risks. We make sure the amount of radiation you receive is as small as possible.

You can read government information about radiation exposure from medical imaging.

The tracer is made from specially-treated human albumin (a protein taken from screened blood donations).

It is perfectly safe for you to travel abroad after your scan, but many airports and sea ports are now equipped with very sensitive radiation detectors. It is possible that the very small amount of radioactivity left in your body could set off a detector as you pass through security. If you plan to travel abroad in in week after your scan, it could be helpful to take your appointment letter with you.

Follow-up appointments

If you already have an appointment booked in clinic to discuss the results of the test, please let our team know.

Your images will be reviewed by our doctors and a report will be sent to the doctor that referred you. You will get the test results from them.

Resource number: 5371/VER1
Last reviewed: July 2023
Next review due: July 2026

Trusted Information Creator. Patient Information Forum

Do you have any comments or concerns about your care?

Contact our Patient Advice and Liaison Service (PALS)

Is this health information page useful?