CT Scan
A CT (computed tomography) scan uses X-rays and a computer to create detailed cross-sectional images of the inside of your body. It does use a small amount of ionising radiation and is valued for showing bones, blood vessels, and many soft tissues quickly and clearly.
Overview
What is a CT scan?
A CT scan is a test that takes a series of X-ray images from different angles and uses a computer to combine them into detailed cross-sectional, or slice-by-slice, pictures of the body. This lets doctors see bones, organs, blood vessels, and soft tissues in much greater detail than a standard X-ray, helping them find and assess many different conditions.
Why is a CT scan done?
CT scans are used to diagnose problems, guide treatment, and monitor how conditions respond to care. They can detect injuries after an accident, find tumours, examine the chest and abdomen, check blood vessels, and help plan surgery or radiotherapy. Because they are quick and detailed, CT scans are often used in emergencies as well as for planned investigations.
Test Details
How do I prepare for a CT scan?
Preparation depends on the part of the body being scanned. For some scans you may be asked not to eat or drink for a few hours, especially if contrast dye will be used. You should remove metal items such as jewellery and wear loose clothing. Always tell staff if you have any allergies, kidney problems, or if you might be pregnant.
What happens during a CT scan?
You lie on a motorised bed that moves slowly through a large, ring-shaped scanner. The machine is open at both ends, so it feels less enclosed than an MRI. You may be asked to hold your breath briefly so the images are sharp. The scan itself usually takes only a few minutes, though the whole visit may take longer if contrast is used.
Results and Follow-Up
What happens after the test, and what do the results show?
You can normally go home and resume your usual activities soon after a CT scan. If you had contrast dye, you may be advised to drink plenty of fluids to help flush it from your body. A radiologist examines the images and sends a report to your doctor. The results can confirm a diagnosis, show the extent of a problem, or guide further tests or treatment, which your doctor will explain to you.
Additional Common Questions
Is the radiation from a CT scan dangerous?
A CT scan uses a small dose of ionising radiation, and the amount is carefully controlled to be as low as possible. For most people the benefit of an accurate diagnosis far outweighs the very small risk.
How long does a CT scan take?
The scan itself is usually quick, often just a few minutes. The full appointment may take longer if you need contrast dye or extra preparation.
Will I have a reaction to the contrast dye?
Most people tolerate contrast dye well. Mild effects such as a warm flush are common and pass quickly, and staff watch closely for the rare allergic reaction, so tell them about any past reactions or allergies.
This health topic is for general information and is not a substitute for professional medical advice. Always consult a qualified clinician about your individual situation. See our medical disclaimer.