If you have a computerised tomography (CT) scan, you will be exposed to radiation in the form of X-rays. The amount of radiation that is used is very small.
Radiation is measured in units called millisieverts (mSv). Different types of CT scan use different amounts of radiation. For example:
- CT scan of the head - 1.4 mSv
- CT scan of the chest - 6.6 mSv
- CT scan of the whole body - 10 mSv
Benefits versus risks
The benefits of having a CT scan to help diagnose a medical condition, or to check the symptoms of an existing condition, will usually outweigh any potential risk. In these cases, CT scans are quick and accurate and often eliminate the need for invasive surgery.
However, if you do not have any symptoms, the benefits of having a CT scan are less clear and may not outweigh the risks, particularly if it leads to further unnecessary testing and added anxiety.
Therefore, the benefits and risks should always be weighed up before deciding to have a CT scan. It is recommended that you only have a CT scan following a medical referral.
Read more about the risks of radiation exposure.
Pregnant women and children
CT scans are not recommended for pregnant women because there is a small risk that the X-rays may harm the unborn child. Before having a scan, you should tell your doctor if there is a chance that you may be pregnant.
Children are at greater risk from a build-up of radiation than adults and should only have a CT scan if it is justified by a serious condition that puts them at an increased risk.
