CT scan (2024)

A CT scan is a test that takes detailed pictures of the inside of your body. It's usually used to diagnose conditions or check how well treatment is working.

Why a CT scan is done

You may be referred for a CT scan to:

  • check your bones or internal organs after an accident
  • find out if symptoms you've been having are caused by a condition, such as cancer
  • see how well a treatment is working, such as checking the size of a tumour during and after cancer treatment
  • help doctors see inside your body during a procedure, such as taking a sample of cells (biopsy) or draining an abscess

Preparing for a CT scan

The hospital where you're having the CT scan will tell you if there's anything you need to do before it.

For example, you may be asked to:

  • follow a special diet
  • take certain medicines
  • not to eat or drink anything for several hours before the scan (fast)
  • not wear anything that has metal in it, such as jewellery, clothes with zips or poppers, bras or hair clips

Tell the hospital if you:

  • are pregnant or might be pregnant
  • are breastfeeding
  • take any medicines
  • have asthma
  • have kidney or thyroid problems
  • have diabetes
  • have any allergies or have had an allergic reaction to a dye called contrast medium before


Talk to a GP or doctor at the hospital if you're feeling anxious about having a CT scan or have a fear of small spaces (claustrophobia). They may be able to give you a medicine to help you relax.

You can also ask if you can bring someone to support you during the CT scan.

What happens during a CT scan

A CT scan is usually done in hospital by a healthcare professional called a radiographer. It usually takes between 10 and 20 minutes.

Before the CT scan

Depending on why you're having a CT scan, you may be given a dye to help show more detail in the CT scan pictures. The dye is called contrast medium.

It can be given to you in a drink, injected into a vein, or be put in your bottom. It'll pass out of your body in your pee.

If the contrast medium is injected into your body, you may feel:

  • hot and flushed
  • like you have a metal taste in your mouth
  • like you're peeing, but you're not

These feelings usually pass quickly.

During the CT scan

CT scan (1)


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  1. You'll be asked to lie on a flat bed.
  2. The radiographer will control the scanner from another room. They'll be able to hear and speak to you during the scan.
  3. You'll need to lie still so the scanner can move over you to take clear images.
  4. You may be asked to breathe in, out, or hold your breath during parts of the scan.

After the CT scan

If you're having the scan as an outpatient, you'll be able to go home soon after you've had the scan.

If you were given contrast medium, you may be asked to wait in the hospital for up to 30 minutes to make sure you do not have a reaction to it.

Getting your CT scan results

It usually takes between 1 and 2 weeks for you to get your CT scan results. The images need to be looked at by a specialist called a radiologist.

The radiologist will write to the doctor who referred you for the scan. You may need a follow-up appointment to talk about your CT scan results.

If you have not heard anything after a few weeks, contact the doctor who referred you.

The doctor should talk to you about your results and explain what happens next.

Sometimes you may need other tests, depending on why you had the CT scan.

Ask to talk to a healthcare professional if you have questions about your results, or do not understand them.

Possible complications of a CT scan

Complications of a CT scan are rare. Some people can have an allergic reaction to the contrast medium (dye). This can cause weakness, sweating and difficulty breathing.

You'll be asked to wait at the hospital for up to 30 minutes after having the scan before you can go home if you had contrast medium.

Tell the radiographer if you feel unwell after the scan.

If you have lots of CT scans, there's a very small chance the radiation from the X-rays can cause cancer. The doctors will weigh up the risks before giving you a scan and discuss this with you.

Page last reviewed: 08 November 2023
Next review due: 08 November 2026

CT scan (2024)


What was the result of CT scan short answer? ›

CT scans can find bone and joint problems, like complex bone fractures and tumors. If you have a condition like heart disease, emphysema, or liver masses, CT scans can spot it or help doctors see any changes. They show internal injuries and bleeding, such as those caused by a car accident.

How soon do doctors receive CT scan results if serious? ›

Getting your CT scan results

It usually takes between 1 and 2 weeks for you to get your CT scan results. The images need to be looked at by a specialist called a radiologist. The radiologist will write to the doctor who referred you for the scan. You may need a follow-up appointment to talk about your CT scan results.

Can CT scans make mistakes? ›

A CT scan can be wrong: it can't tell the difference between cancerous tissue and non-cancerous tissue. CT scans can be misread or misinterpreted. Imaging tests usually can't tell if a change has been caused by cancer. CT scans can produce false negatives and false positives.

How many CT scans per year are safe? ›

There is no recommended limit on how many computed tomography (CT) scans you can have. CT scans provide critical information. When a severely ill patient has undergone several CT exams, the exams were important for diagnosis and treatment.

What is a CT scan short answer? ›

Computed tomography is commonly referred to as a CT scan. A CT scan is a diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce images of the inside of the body. It shows detailed images of any part of the body, including the bones, muscles, fat, organs and blood vessels.

Will a radiologist tell you if something is wrong? ›

If the radiologist confirms the emergency, you'll be sent for emergency care. But it's simply not their position to share diagnostic information with a patient. “Your test needs to be read by a diagnostic radiologist, and the results go back to your physician.

Can a CT scan give false results? ›

One potential risk of low-dose CT is that it results in many false-positive findings, such as a lung nodule, that, upon further testing, turns out not to be cancer.

Do all tumors show up on CT scans? ›

Where MRI really excels is showing certain diseases that a CT scan cannot detect. Some cancers, such as prostate cancer, uterine cancer, and certain liver cancers, are pretty much invisible or very hard to detect on a CT scan. Metastases to the bone and brain also show up better on an MRI.

What are 2 risks of a CT scan? ›

Risks of CT Scan

Radiation exposure during pregnancy may lead to birth defects. If contrast dye is used, there is a risk for allergic reaction to the dye. Patients who are allergic to or sensitive to medications, contrast dye, iodine, or shellfish should notify their physician.

How long does radiation stay in your body after a CT scan? ›

Does any radiation stay in the body after an imaging exam? After a radiographic, fluoroscopic, CT, ultrasound, or MRI exam, no radiation remains in your body. For nuclear medicine imaging, a small amount of radiation can stay in the body for a short time.

How to get rid of radiation after CT scan naturally? ›

Eating an antioxidant-rich diet before and after your CT scan can help increase your body's ability to get rid of radiation. Vitamin E and vitamin C are also especially helpful when it comes to protecting your body.

Is MRI safer than CT scan? ›

Unlike X-rays and CT scans, MRIs don't use any radiation. At Johns Hopkins, we've developed very fast, high-resolution MRIs that can be done in 10 minutes or less. An MRI scanner is a highly specialized machine and may not be available in some imaging facilities or emergency rooms at other hospitals.

What results come from a CT scan? ›

CT scans help healthcare providers detect various injuries and diseases, including: Certain types of cancer and benign (noncancerous) tumors. Fractures (broken bones). Heart disease.

What is the result of CT scan in Chapter 3? ›

(ii) What were the results of the CT scan? Ans: The C.T. scan machine scanned Tut's mummy from head to toe. It created 1,700 digital X-ray images in cross-section and Tut's head was scanned in 0.62-millimeter slices and produced images in eerie detail.

What was the result of CT scan of King Tut? ›

The results of a CT scan done on King Tutankhamun's mummy indicate the boy king was not murdered, but may have suffered a badly broken leg shortly before his death at age 19 - a wound that could have become infected, Egypt's top archaeologist said today.

How do you describe CT scan findings? ›

The appearance of tissues on a CT scan is described in terms of 'density'. Darker structures are 'hypodense or low density'; brighter structures are 'hyperdense or high density'. Blood Can Be Very Bad is a mnemonic that can be used when faced with interpreting a CT head scan: Blood.

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