A computerised tomography (CT) scan uses X-rays and a computer to create detailed images of the inside of the body.
CT scans are sometimes referred to as CAT scans or computed tomography scans.
They're carried out in hospital by specially trained operators called radiographers and can be done while you're staying in hospital or during a short visit.
CT scans can produce detailed images of many structures inside the body, including the internal organs, blood vessels and bones.
They can be used to:
- diagnose conditions – including damage to bones, injuries to internal organs, problems with blood flow, strokes and cancer
- guide further tests or treatments – for example, CT scans can help to determine the location, size and shape of a tumour before having radiotherapy, or allow a doctor to take a needle biopsy(where a small tissue sample is removed using a needle) or drain an abscess
- monitor conditions – including checking the size of tumours during and after cancer treatment
CT scans wouldn't normally be used to check for problems if you don't have any symptoms (known as screening). This is because the benefits of screening may not outweigh the risks, particularly if it leads to unnecessary testing and anxiety.