This page gives you information about having a Computed Tomography (CT) scan of the head or sinuses. It explains how the procedure is carried out and some of the possible risks.

What is a CT scan?

A CT (Computed Tomography) scanner is an X-ray machine which produces images (pictures) of the inside of the body. The scanner is made up of a ‘doughnut’ shaped structure (gantry), about 2 feet thick and a couch on which you will be asked to lie. This couch will pass through the scanner.

See the image within the PDF below, Doughnut shaped structure which you will pass through

A narrow fan-shaped beam of X-rays is produced from inside the gantry and rotates in a complete circle around you.

The X-rays pass through your body and are detected by electronic sensors on the other side of the gantry. The information passes to a computer which then produces a picture of the internal structures of the body. The pictures are displayed on a computer and can be examined by the radiologist.

It takes less than a second to produce each slice, which can vary in thickness from one millimetre to one centimetre. Depending on how much of the body is being scanned, it may be necessary to produce 1000 or more images. Most modern CT scanners can do this in less than a minute so the actual scanning time is short.

Are there any risks?

CT scanning uses X-rays; this is a form of ionising radiation. The amount of radiation is equal to the natural radiation we all receive from the atmosphere over a period of about 3 years. This adds very slightly to the lifetime risk of developing a cancer. However, Cancer Research UK predicts that 1 in 2 of us will develop a cancer at some stage during our lives, so this additional risk is very small (about 1 in 2000 after 20 years).

This examination has been considered beneficial for you and the need outweighs the risks associated with radiation.


It is important that all patients of childbearing potential are scanned within the first 28 days of their menstrual cycle. If you are under 56 years of age and your appointment does not lie within this time-frame or you are or may be pregnant please call the CT appointments team to discuss or reschedule.

Are there any special preparations?

Please remove any items of jewellery from your head and neck before attending for your appointment as we are unable to offer secure facilities for safe storage of valuables in the department. You will be asked to remove them before having your scan if worn.

Can I bring a relative or a friend?

Please attend the department alone unless a carer is required, however for safety reasons they cannot join you in the CT scanning room. Any other persons accompanying you may be asked to wait outside the department during your examination.

When you arrive

It is important to let a member of the team know if you are pregnant, or even if there is a chance that you might be pregnant. Similarly, you should let the team know if you have diabetes, asthma or any allergies.

Please bear in mind we cannot accept responsibility for children under 16 within the department while you are having your examination.

Who will I see?

You will be cared for by a small team including a radiographer, nurse and radiographic care assistant. A radiologist will review the images later before writing a report on the findings.

What happens during the CT scan?

You will be taken to the scanning room and made comfortable lying on the couch with your head supported in a holder. The couch will be moved slowly to position your head within the ‘doughnut’.

The radiographers will move to the adjoining control room but you will be able to talk to them via an intercom and they will be observing you at all times.

During the scan you may be asked to keep still.

Commonly asked questions

Will it be uncomfortable?

You should not feel any pain, although some people do have slight discomfort from having to lie still.

Most patients do not mind lying with part of their body within the scanner, but if this makes you feel anxious please tell the radiographer straight away.

How long will it take?

The whole scanning process will take about 10 minutes, unless you are delayed due to an emergency patient.

How long will it take?

The whole scanning process will take about 10 minutes, unless you are delayed due to an emergency patient.

Are there any side effects?


Can you eat and drink afterwards?


When will I get the results?

After your visit, the radiologist will look at your CT scan and prepare a report on the findings. This will be sent to your referring doctor. The radiographer is unable to give you any results after your scan.

Contact information

If you have any questions about having the CT scan, please contact the CT Appointments Team on the number shown on your appointment letter. Calls can be made Monday to Friday between 9:00am and 5:00 pm.


If you do not believe you should have been referred for this procedure please contact the CT department immediately.

We are pleased that we can offer state of the art technology for diagnosis. However, radiology equipment needs constant updating and there is a charitable fund for this. If you would like to make a donation, please send a cheque to the address below. Cheques should be made payable to GHNHSFT.

Administration Manager

Dept of Radiology (Imaging 1), Gloucestershire Royal Hospital,, Great Western Road, Gloucester, GL1 1NN

Printable version of this page

Adult patients having a CT scan of the head or sinuses Department: Radiology Review due: October 2024 PDF, 818.8 KB, 4 pages
Reference number GHPI0610_10_21
Department Radiology
Review due October 2024