CT scan

A CT (computerised tomography) scan is a test that takes detailed pictures of the inside of your body [1]. It combines a series of X-ray images taken from different angles, which a computer turns into cross-section "slices" showing bones, organs and soft tissue [1].

CT scans are used to look at bones and organs after an injury, to help diagnose conditions such as cancer, to check how well a treatment is working, and to guide other procedures such as taking a biopsy or draining an abscess [1].

The hospital will tell you if you need to do anything beforehand, such as following a special diet or not eating for a few hours [1]. Let the staff know in advance if you are or might be pregnant, if you are breastfeeding, or if you have asthma, diabetes, kidney or thyroid problems, or any allergies — particularly to the contrast dye that is sometimes used [1].

You lie still on a flat bed that moves slowly through a ring-shaped scanner [1]. The scan is painless and usually takes about 10 to 20 minutes [1]. You may be given a contrast dye by injection, as a drink or into your bottom to make certain areas show up more clearly, which can make you feel warm or leave a metallic taste for a short while [1].

The images are studied by a radiologist, who sends a report to the doctor who arranged your scan [1]. Results are not usually available straight away and often take a week or two, sometimes longer [1].

CT scans are generally very safe. A reaction to the contrast dye is possible but uncommon [1]. The scan uses a small amount of radiation, and having many scans over your lifetime carries a very small increased risk of cancer — your doctor will only recommend a scan when the benefit outweighs this risk [1].