Lung VQ Scan

What is a Lung VQ Scan?

A lung VQ scan looks at the air supply and blood supply to the lungs. It determines the likelihood of having a pulmonary embolism, a blood clot in the lung. Additionally, a VQ scan can also be used to assess lung function.


There is no special preparation for the examination.


If you are pregnant or breastfeeding it is essential that you let us know before your appointment date. If you are a female of child bearing age (12-55 years old) you will be asked about your pregnancy and breastfeeding status. If you are unable to confirm you are not pregnant a pregnancy test may be performed.


All patients are entitled to have a chaperone.

The examination

Your lung examination has two parts – one that looks at the airflow into the lungs and one that looks at the blood flow to the lungs.

Upon your arrival a radiographer will explain the procedure to you and will ask you a few questions about your health records. You will be asked to lie down and then to breathe a small amount of a radioactive gas through a mouth piece which shows us the airflow into the lungs.

After the inhalation portion, you will be taken into the scan room, positioned on the scan table and a series of pictures are taken of your lungs. The machine is very quiet and you do not go through a tube or tunnel.

After the first set of images you will be given a small amount of radioactive tracer injected into a vein in your arm while lying on the scan table which shows us the blood flow to your lungs. The injected tracer is carried through the bloodstream to your lungs and another series of images are acquired.

How long will it take?

The examination will take approximately 20-40 minutes

Who will be present?

Your scan will be performed by a Nuclear Medicine trained member of staff which stays with you in the room while scanning.

Is radioactivity dangerous?

The amount of radiation involved is similar to that from an x-ray examination. The radioactivity naturally disperses from the body and is largely gone in 24 hours. The very low risk involved is balanced against the benefit of the information the examination provides for your doctors.