CT scan 

Introduction 

During a CT scan, a series of X-rays are taken to produce a detailed image called a tomogram 

Radiologists and radiographers

The radiology department, also known as the X-ray or imaging department, is the area of a hospital where radiological examinations are carried out. These include X-rays, ultrasound scansMRI scans and CT scans.

Radiologists are doctors trained to carry out and interpret medical images, such as X-rays and CT scans. They're supported by radiographers, who are trained to carry out X-rays and use other types of scanning equipment.

A computerised tomography (CT) scan uses X-rays and a computer to create detailed images of the inside of the body. 

CT scans are also sometimes known as CAT scans, which stands for computerised axial tomography.

During a CT scan, you'll usually lie on your back on a flat bed. The CT scanner consists of an X-ray tube that rotates around your body. You'll usually be moved continuously through this rotating beam.

The X-rays will be received by a detector on the opposite side of your body and an image of the scan will be produced by a computer.

Unlike an MRI scan, where you're placed inside a tunnel, you shouldn't feel claustrophobic.

The images produced by a CT scan are called tomograms and are more detailed than standard X-rays. A CT scan can produce images of structures inside the body, including the internal organs, blood vessels, bones and tumours.

The scan is painless and will usually take between five and 10 minutes depending on the part of your body being scanned.

Read more about how a CT scan is performed.

When CT scans are used

CT scans can be used to diagnose and monitor a variety of different health conditions, including brain tumours, certain bone conditions, and injuries to internal organs such as the kidneys, liver or spleen. They're also now being used to look at the heart.

They're also often used to look inside the body before another procedure takes place, such as radiotherapy treatment or a biopsy (where a small sample of tissue is taken so that it can be examined under a microscope).

Read more about when you might need a CT scan.

Your results

CT scans are usually carried out on an outpatient basis, which means you'll be able to go home on the same day as the procedure.

Your scan results won't be available immediately. A computer will need to process the information from your scan, which will then be analysed by a radiologist (a specialist in interpreting images of the body).

After analysing the images, the radiologist will write a report and send it to your doctor. This usually takes a few weeks.

Safety

CT scans are only used when the doctor responsible for your care decides there's a clear medical benefit.

Although CT scans are generally safe, they do expose you to slightly more radiation than other types of imaging tests. The amount of radiation you're exposed to can vary depending on the type of scan you have.

In most cases, the benefits outweigh any potential risks because a CT scan can provide your doctor with much clearer images than those produced by a normal X-ray.

However, CT scans aren't routinely recommended for pregnant women because there's a risk that the X-rays could harm the unborn baby.

Children are also more at risk of developing a build-up of radiation than adults. A CT scan will therefore only be recommended if a child has a serious condition that puts them at greater risk.

Read more about the risks of CT scans.

Page last reviewed: 17/10/2013

Next review due: 17/10/2015

Ratings

How helpful is this page?

Average rating

Based on 604 ratings

All ratings

Add your rating

Comments

The 10 comments posted are personal views. Any information they give has not been checked and may not be accurate.

EiramReves said on 12 January 2014

Can someone tell me if there is a maximum weight limit of patients using CT scanner and MRI scanner please?
Thanks

Report this content as offensive or unsuitable

ladyjo04 said on 16 September 2013

I had a CT scan after having pins & needles in arms & legs & a suspected stroke. I had Iodine injected into me whilst lying down & it went into veins then into head allowing my brain to be lit up & them see clearly any defect or illness.

The weird sensation is the only way of explaining the feeling of the iodine been injected in me & metal taste of copper in mouth.

I could feel it running through my body. It only lasted 20 seconds whilst the scanner did it things. I was nervous to say the least but, i had no after effects of this & went home the same day.

Report this content as offensive or unsuitable

DianaO said on 26 March 2012

I think the CT scans are part of becoming healthy even if it does come with some radiation. It seems like the amount of radiation that CT scan provides will not kill me tomorrow but a tumor might. Anyway there are hundreds of risky health procedures and it's not going to stop any of us to choose to take the risk just to be healthy. Since these machines are so expensive most care givers use used CT equipment and I think that's more alarming then the radiation.

Report this content as offensive or unsuitable

User646087 said on 16 February 2012

With reference to this post:
simm1 said on 08 October 2011
The above text says ''The amount of radiation you are exposed to is safe and is not enough to cause any harm. This is obviously not true. In order to have informed choice, patients need to have access to raw facts and data which helps them to weigh risks versus benefits.
_________________
I would agree. While the risk of inducing a cancer from the xrays used in a CT scan is small over a person's lifetime, it is still present and sometimes much much greater than that of a chest x-ray (although still small). As part of informed consent, patients would need to have access to risk and benefit information, for example.

Likewise a CT scan may be absolutely appropriate for a pregnant woman, if the risk to her of a having a diagnosable but mis-treated condition is greater than the ionising radiation risk from the xrays used.

The Ionising Radiations Medical Exposures Regulations (2000) protect the public with the specialist expertise of medical physics professionals, Radiologists, Oncologists and last but not least, Radiographers.

Report this content as offensive or unsuitable

Gill59 said on 23 November 2011

To Simm1 - if you took the time to read all the information here (especially the 'Risks' area) you would have all the information you needed to make an informed choice - even the results of clinical trials. I now feel very comfortable that I know what to expect tomorrow and that the procedure has been offered to me in my own best interests! If I feel differently afterwards - watch this space!

Report this content as offensive or unsuitable

simm1 said on 08 October 2011

The above text says ''The amount of radiation you are exposed to is safe and is not enough to cause any harm.
This is obviously not true. In order to have informed choice, patients need to have access to raw facts and data which helps them to weigh risks versus benefits.

Report this content as offensive or unsuitable

yasasii said on 28 July 2011

I was put in a ct scanner for no reason that I am aware of,hospital refuse to tell me if I was sedated,had contrast injcted or was restrained,all of which I think are true.I was ill and could not stop them,they knew I did not consent.
I now have flashbacks and cannot sleep for the fearful visions that I have.night after night.

Report this content as offensive or unsuitable

medoo said on 03 July 2011

Dear all ,
could you kindly tell me , why we use couch that is flat for CT simulator and curved couch for diagnostic purposes

and what is the difference between them clinically and physically .

thanks !

Report this content as offensive or unsuitable

princess99 said on 13 April 2011

do you have to have radioactive stuff injected into your body before a CT scan ?

Report this content as offensive or unsuitable

princess99 said on 13 April 2011

do you have to have radioactive stuff injected into you ?

Report this content as offensive or unsuitable

X-ray

Bone is a hard, dense tissue that shows up clearly on X-rays, making them very useful for diagnosing bone-related problems

MRI scan

An MRI scan uses strong magnetic fields and radio waves to produce detailed images of the inside of the body