This type of lung scan allows us to look at air taken in by the lungs and identify any problems with it. 

How does it work?

Your child will lie down on a scanner couch and be asked to breathe a small amount of radioactive gas called krypton-81m through a standard oxygen mask placed over his / her nose and mouth. To get the clearest pictures, we need your child to stay still for the scan and we may ask for your help with this. Wherever possible we will ask you to hold the mask for your child as we find this makes it less stressful for both of you. The krypton gas is odourless and tasteless, so breathing it will feel exactly like breathing air. Only a small part of the gas your child will breathe in is krypton gas – most will be ordinary room air – so your child will be able to breathe normally without any impairment.

We usually take two pictures during the scan and your child will need to inhale the krypton gas for about two minutes for each picture. While he/she is inhaling the gas, the camera will be placed over his/her chest for the first image and then under the couch for the second. The scan will take about 15 minutes in total because we change the position of the camera between pictures.

You will be able to stay with your child throughout the scan.

How do we prepare?

There is no specific preparation for this scan. Our staff will explain the procedure to you fully when you arrive for your child’s appointment. 

It is important that your child lies as still as possible during the scan. The technologist will help to make them comfortable and we may ask for your help in this. 

If there are any metal objects on your child’s clothing that cannot be removed, we may ask him/her to change into something more suitable if appropriate.  

Special instructions for parents

  • If you are the child’s mother and there is any chance you are pregnant, please let us know before the scan starts. If you are, we may ask another person to assist with your child’s scan. 
  • Unless you really need to, please do not bring other children to the department.

After the procedure

Once your child’s scan is finished, its quality will be checked while you wait. The technologist will provide a copy of the pictures for you to give to the doctor in the clinic. 

The radiation dose from this procedure is very small so there is no need to make any change to your child’s normal routine. There will be no radioactivity left in their lungs at the end of the procedure.

Your child will not experience any side effects from inhaling the krypton gas and he/she will be able to eat and drink normally and return to normal activities after the scan. 

There are currently no related conditions associated with this test.

Royal Brompton nuclear medicine

Level 3, Chelsea Wing, Sydney Street


Monday to Friday, 9am to 5pm

Tel: 020 7351 8666 / 9
Fax: 020 7351 8668
Patient advice line: 020 7351 8667

If you have any questions or concerns about the scan please call our patient advice line.

It is an answerphone service – leave a message and we will call you back within 24 hours.

Department head

Kshama Wechalekar