Your Doctor or Healthcare Professional has asked that you have a test which uses ionising radiation.

There are different types of tests that use radiation; this page will briefly describe them and will explain a little about the benefits and risks of having your test.

Tests which use ionising radiation include X-rays, Computerised Tomography (CT) scans, Positron Emission Tomography and CT (PET-CT) Scans. Magnetic ResonanceImaging (MRI) scans and Ultrasound scans do not use ionising radiation.

For the most common type of imaging scans, such as arms, legs, chest or teeth the radiation dose is very low and any increased risk from radiation is very small. Scans that use more radiation are usually scans for more serious illnesses, but even for these scans, for example, CT scans or PET-CT scans, of the whole body, the risk is still low.

Each X-ray or scan gives us an additional dose of radiation, on-top of any natural background radiation we receive as part of our everyday lives. Generally, this extra dose would be equal to between a few days and a few years of any natural background radiation.

All healthcare staff that you meet as part of your scan have been trained in the use of radiation for medical imaging. Before any scan, the healthcare professional will make sure that the scan requested is the one which will most likely answer the clinical question and provide the most successful results in terms of a diagnosis. Any risks will be controlled and benefits maximised, using the lowest radiation dose possible, whilst making sure that the images are of diagnostic quality, providing the information required.

If an unborn baby receives a radiation dose from a diagnostic medical scan this may cause a slight increase in the risk of cancer to the baby. Scans therefore of the abdomen and/or pelvis are not usually performed when pregnancy is possible or known, unless the risk of not performing the scan is greater. Scans of areas well away from the abdomen do not provide any serious increased risk of harm to an unborn baby.

Some typical doses received are given in the table below, compared with the UK average annual radiation dose from natural radiation of 2.7 mSv.

Comparisons:

(Test - Typical average dose mSv - Comparison Dose)

Dental X-ray - 0.005 mSv - Less than eating 100g of Brazil nuts

Chest X-ray - 0.014 mSv - Less than a transatlantic flight

CT scan of head - 1.4 mSv - Less than the annual average natural background radiation in the UK

Whole body PET-CT Scan - 20 mSv - Equal to roughly 8 years natural background radiation in the UK