Computerised tomography


Computerised tomography (CT) is a test that uses x-ray equipment and computer software to create three-dimensional views of the inside of the body.

The CT scanner is a ring-shaped machine. Inside the ring is an x-ray tube that produces a fan-shaped beam of X-rays. The tube rotates around the body creating individual pictures that are cross-sectional ‘ slices’ throughout the body.

CT scans

Referral criteria

Requests and results

Contact information



CT scans

The images from CT are black, white and grey, as with plain x-rays, but the computer joins the slices together to give three-dimensional views. This means that a CT scan allows doctors to see the height, width and depth of something inside the body.

The images are kept in a digital format and shown on a computer screen.

CT scanning is a high radiation dose investigation, and requires careful patient selection for this reason.  It is important that the criteria is read and considered carefully.

The services is only available at Croydon University Hospital and the maximum waiting time for this service is four weeks.



Referral criteria

Indications for direct access CT:

  • Report of a direct access imaging investigation advises a CT scan in order to avoid delays in the patient pathway

  • Headaches according to agreed referral criteria (see below)

Indications for referral for direct access head CT:

Red flag features:
  • New headache with known active or potentially active malignant disease or HIV.
  • New headache with persistent vomiting.
  • New headache with significant focal signs or symptoms.
  • New headache with papilloedema
  • New headache with history compatible with raised intracranial pressure such as worse on coughing, sneezing, bending or straining, and woken up by headache in the early hours of the morning.

Non red flag headaches:

  • Failure of conventional treatment for benign headaches (reasonable trial of anti-migraine drugs, tricyclic agents and analgesic withdrawal)
  • Concern that patient cannot be reassured that they do not have a brain tumour without CT scan
  • GP feels that they can manage benign headache without referral to secondary care with normal brain CT


Requests and results

There are two ways of organising a direct access CT scan:

  • via Sunquest ICE (preferable)

  • by completing the referral form on the right of this page and faxing it to the hospital on fax no. 0208 401 3454

Results and reports are sent back to GPs via Sunquest ICE.

For downtimes procedures click here.


Contact information

Croydon University Hospital

530 London Road




Tel: 020 8401 3049


Service Leads

Operational Manager for Diagnostic Imaging

Deanna McCready

Tel: 020 8401 3465

Consultant Radiologist/Clinical Lead

Dr S Maheshwaran

Tel: 020 8401 3000 ext.4122



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