Scans like X-rays and computerised tomography (CT) scans are used to create pictures of the inside of your body.
You’ll usually have your scan in a hospital radiology department with a specialist called a radiographer.
It can be worrying to be told you need a lung scan. You may feel nervous and have lots of questions or feel frustrated if you have to wait a long time to get the test done. Find out how to get support and look after yourself during this time.
Why do I need a lung scan or X-ray?
There are lots of reasons you may need a scan or X-ray. Lung scans help healthcare professionals find out more about what’s happening in your lungs.
This may include things like:
- understanding more about why you’re having symptoms like breathlessness or coughing up phlegm
- monitoring your lung condition and checking how your treatment is working for you
- looking for different lung conditions, including chronic obstructive pulmonary disease (COPD), bronchiectasis, pulmonary fibrosis, pulmonary hypertension, and lung cancer
- checking for lung infections like pneumonia.
Your healthcare team should tell you why they’re referring you for a lung scan.
Your healthcare team will do other tests to confirm any diagnosis. These tests will depend on what lung condition you may have. Find out more about tests for diagnosing lung conditions.
| Type of scan | What does the scan show? | Why may I need this scan? | How long will the scan take? |
|---|---|---|---|
| Chest X-ray | An image of your lungs, ribs, heart and the muscle below your lungs (diaphragm). |
To help healthcare professionals understand more about why you’re having symptoms, like breathlessness, chest pain, or coughing up phlegm or blood. They can also see if you have a lung infection, like pneumonia. |
A few minutes |
| CT scan – this is a more detailed version of an X-ray | A three-dimensional (3D) image of your lungs, blood vessels and other organs. |
To help healthcare professionals diagnose or monitor lung conditions, plan your treatment or check how well it’s working. It can also show areas where you may have inflammation in your lungs. |
10 to 20 minutes |
| PET (positron emission tomography) scan | 3D images of how active your cells are in your body. | To help healthcare professionals see inflammation, infection or scarring in your lungs, diagnose lung conditions, or plan your treatment and check how well it’s working. | 30 minutes to 1 hour |
| VQ scan – also called a ventilation-perfusion scan | The flow of air and blood supply in your lungs. |
The most common use for a VQ scan is to see if there are blood clots (pulmonary embolism) in your lungs. If you have emphysema, a VQ scan can help find out if you can have a lung volume reduction surgery. |
About 1 hour |
What are the risks of lung scans?
Lung scans are generally safe but, like all medical tests, they do have some risks.
Healthcare professionals will only refer you for a scan if they believe that the benefits for your health outweigh the risks. They will explain these benefits and risks to you before your scan.
Always speak to your healthcare professional if you have any questions or worries about your scan.
Radiation
Scans like X-rays, CT scans, PET scans and VQ scans use very small amounts of a type of radiation called ionising radiation to create images.
The risk from this radiation is very low, but it can very slightly increase your risk of getting cancer in the future.
Healthcare professionals must follow rules on how to do scans and X-rays that use radiation safely. Radiographers are also trained to use the lowest amount of radiation possible to get a good picture.
Find out more about radiation from the Public Health England website.
Pregnancy and breastfeeding
It’s important to tell your healthcare professional and radiographer if you’re pregnant or think you might be, or if you’re breastfeeding.
This is so that your healthcare team can decide when it’s best for you to have your scan and what radiation dose to use.
If you had a PET or VQ scan, you may be asked to avoid anyone who is pregnant, babies and children for a few hours after your scan. This is while the radiation leaves your body. If you have children, it’s important to organise childcare to cover this time.
Drinking plenty of water can help the radiotracer to leave your body.
Allergies
In rare cases, some people may have an allergic reaction to something used in a lung scan.
You may be asked to stay at the hospital after your scan so that your healthcare team can make sure you’re well enough to go home. Your radiologist is trained to deal with allergic reactions.
You may be given a special dye to improve the quality of the CT scan image. Healthcare professionals will usually give you the dye through an injection into one of your veins or as a drink.
The dye is normally harmless and will leave your body through your pee. This dye sometimes contains a natural mineral called iodine.
In rare cases (less than 1 in 100), some people may have an allergic reaction to the dye.
You will be given a liquid called radioactive tracer if you’re having a PET or VQ scan. This helps to create the image for the scan. Healthcare professionals will usually give you the liquid through an injection into a vein in your arm.
The tracer is safe and most of it will leave your body within 24 hours.
In very rare cases, some people may have an allergic reaction to the radioactive tracer.
Tell your radiographer and hospital staff if you:
- are allergic to anything, including iodine, before your scan
- start to feel unwell during the scan.
How can I prepare for my lung scan?
You should get a letter from the hospital telling you about your appointment and how to prepare for your scan. Read this carefully because it’ll tell you if there’s anything you need to do before the test.
How to prepare depends on the test you’re having and your hospital. You’ll usually be able to go home soon after your scan.
Always speak to a healthcare professional if you have any questions about how to prepare or if you’re worried about your scan. Your radiographer can help you feel more comfortable for the test, for example by giving you medicine to help you relax or checking if you can have someone else in the room with you.
Speak to your GP or the healthcare professional who referred you for your scan if you need help getting to and from the hospital. Some hospitals can organise free transport to and from the hospital.
It’s especially important to arrive on time for your PET scan. This is because the radioactive liquid used in the scan is prepared before the appointment and only works for a short amount of time. If you’re late or there are other delays in getting the liquid for the scan, you may have to reschedule your appointment.
Find out about how to prepare and what happens during and after:
Your lung scan results
You will not usually get the results of any lung scans straight away. This is because a specialist radiologist will review your scans and report them to your doctor.
The time it takes to get your results can depend on the type of scan you have, where you have it, and how urgent it is.
Your healthcare team should discuss your results with you and explain what happens next.
Contact your hospital or GP if you have not heard anything a few weeks after having your scan.
You may find it helpful to ask your specialist to copy you into any letters about your lung scan that they send to your GP or other healthcare professionals. These letters may also be available on your NHS app.
Results are not the same as diagnosis
You may get your test results by post or through the NHS app. Remember that these results are not the same as a diagnosis.
It’s still important to talk to your healthcare professional about your results so they can help you understand what they mean and answer any questions you have.
Looking after yourself
People sometimes tell us that it can feel worrying to get referred for a lung scan. It may also be stressful to wait for your results after the scan. It’s important to speak to someone you trust about how you’re feeling.
You can also find help and support through our:
- online communities on Health Unlocked – we have forums for people with asthma and other lung conditions to chat to each other, get support and share ideas
- support groups – we have many online and in-person support groups for people with lung conditions
- helpline – you can talk to our helpline about any aspect of your lung condition, or about how you’re feeling.
Find out more about looking after your mental health, including practical advice to improve your emotional wellbeing.
How we develop our health information
About our health information
All our information is reviewed and updated by Asthma + Lung UK’s experienced Health Advice Team. People living with lung conditions, qualified healthcare professionals and specialists also review our content.
This information has been clinically reviewed by Dr Andy Whittamore, a GP with a specialist interest in respiratory medicine.
Our information is based on the latest, trustworthy evidence and guidelines. Below is a sample list of the sources referenced in our scans and X-rays for lung conditions information.
- Tarnoki et al., Breathe, Vol 20 (3), Lung imaging methods: indications, strengths and limitations | European Respiratory Society, Published: 2024
- UK Statutory Instruments, The Ionising Radiation (Medical Exposure) Regulations, Published: 2017
- King’s College Hospital, NHS Foundation Trust, General imaging, Accessed: April 2026
If you'd like a full list of the sources we've used to produce our health information, you can email us at healthadvicequeries@asthmaandlung.org.uk.
Get support
Call or email our helpline for support with any aspect of living with a lung condition – whether you need practical advice, emotional support, or answers to health-related questions. You can also find support through our groups.
