CT Scans

If you've been referred for a CT scan, it's likely that your doctor wants to get a better look at what's going on inside your body. A CT scan is a type of imaging test that uses X-rays and computer technology to create detailed images of your internal organs, bones, and tissues. You may be referred for a CT scan if you have symptoms like pain, swelling, or abnormal growths, or if you need to be screened for certain conditions or diseases. During the scan, you'll lie down on a table that slides into a large, doughnut-shaped machine that takes pictures from different angles. It's painless and usually takes less than 30 minutes.

At Blackrock Health, we understand that waiting for diagnostic results can be stressful. That's why we offer fast access to our state-of-the-art facilities in Blackrock, Galway, Hermitage and Limerick. Across our three hospitals and our diagnostic clinic, we are committed to ongoing investment in imaging and lab tests. By offering some of the most advanced imaging and diagnostic technology, we aim to provide accurate and timely diagnoses. Our team of experts has the capacity and expertise to perform, analyse, and report results for a wide range of tests. This ensures that you can receive the highest possible standards of care and support. Whether you need routine tests or more urgent imaging, we aim to give you the reassurance of a result with the least possible delay. 

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.

When CT scans are used

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, stroke, and cancer,
• monitor conditions, including checking the size of tumours during and after cancer treatment.
• as a guide for further tests or treatments.

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 chances of finding an abnormality when there are no symptoms is low. Also, the benefits of screening may not outweigh the risks, particularly as there is radiation involved.

Blackrock Health use the referral criteria, ‘iRefer Guidelines, Making the Best Use of Clinical Radiology’. These guidelines are considered when requesting a diagnostic radiology/nuclear medicine examination.

Preparing for a CT scan

Your appointment letter will mention anything you need to do to prepare for your scan.

You may be advised to avoid eating anything for several hours before your appointment to help make sure clear images are taken.

You should inform Blackrock Health if you have any allergies, kidney problems, heart failure, high blood pressure or if you’re taking medication for diabetes, as special arrangements may need to be made, or you may need a blood test done in advance of your scan. Some scans involve injection of a contrast or dye, which is excreted through the kidneys, so we want to ensure they are functioning sufficiently.

You should also let the hospital know if you’re pregnant. CT scans aren’t usually recommended for pregnant women unless it’s an emergency, as there’s a small chance the as there’s a small chance the radiation could harm your baby.

It’s a good idea to wear loose, comfortable clothes as you may be able to wear these during the scan.

Try to avoid wearing jewellery and clothes containing metal (such as zips), as these will need to be removed.

Before having a CT scan – Oral and IV Contrast

Before having the scan, you may be given a special dye called a contrast to help improve the quality of the images.

This may be swallowed in the form of a drink, passed into your bottom (enema), or injected into a blood vessel.

Tell the radiographer if you feel anxious or claustrophobic about having the scan.

Before the scan starts, you may be asked to remove your clothing and put on a gown.

You’ll also be asked to remove anything metal, such as jewellery, as metal interferes with the scanning equipment.

What happens during a CT scan

During the scan, you’ll usually lie on your back on a flat bed that passes into the CT scanner.

The scanner consists of a doughnut-shaped ring that rotates around a small section of your body as you pass through it.

Unlike an MRI scan, the scanner doesn’t surround your whole body at once, so you shouldn’t feel claustrophobic.

The radiographer will operate the scanner from the next room. While the scan is taking place, you’ll be able to hear and speak to them through an intercom.

While each scan is taken, you’ll need to lie very still and breathe normally. This ensures that the scan images aren’t blurred.

You may be asked to breathe in, breathe out, or hold your breath at certain points.

The scan will usually take around 10 to 20 minutes.

What happens afterwards

You shouldn’t experience any after-effects from a CT scan and can usually go home soon afterwards. You can eat and drink, go to work and drive as normal.

If a contrast was used, you may be advised to wait in the hospital for up to an hour to make sure you don’t have a reaction to it.

The contrast is normally completely harmless and will pass out of your body in your urine.

Your scan results won’t usually 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 the doctor who referred you for the scan so they can discuss the results with you. This normally takes a few days or weeks.

Are CT scans safe?

CT scans are quick, painless and generally safe. But there’s a small risk you could have an allergic reaction to the contrast dye used and you’ll be exposed to X-ray radiation.

The amount of radiation you’re exposed to during a CT scan varies, depending on how much of your body is scanned.

CT scanners are designed to make sure you’re not exposed to unnecessarily high levels.

Generally, the amount of radiation you’re exposed to during each scan is the equivalent to between a few months and a few years of exposure to natural radiation from the environment.

It’s thought exposure to radiation during CT scans could slightly increase your chances of developing cancer many years later, although this risk is thought to be very small (less than 1 in 2,000).

The benefits and risks of having a CT scan will always be weighed up before it’s recommended.

Talk to your doctor or radiographer about the potential risks beforehand if you have any concerns.

Specialist Cardiac CT Scans

At certain locations, Blackrock Health also carry out Cardiac CT scans for our heart patients. You can learn more about this here.