A CT scan can be used to diagnose or monitor health conditions. It can also act as a guide for tests or specific treatments. CT scans can be used for, amongst other things, detecting cancer, examining patients who have experienced physical trauma and early detection of vascular disease.
A CT scan works by using X-rays to examine parts of the body. Different areas of the body absorb X-rays at different rates which produces an electronic image on a screen for examination. Numerous X-ray beams and detectors are passed through the body. CT scanners work quickly through even large sections of the body.
You will be advised if you need to abstain from eating or drinking prior to your CT scan. Any pre-existing illnesses or conditions should be discussed with your radiographer before undergoing the procedure. Patients will be asked to remove anything that could affect the scan. For example: jewellery, glasses, hearing aids, dental works (if possible), hair accessories.
During a CT scan you will be required to lie on a flatbed. The CT scanner, which is shaped like a ring, passes over the body but does not cover the entire body at any time. Patients are able to talk to the radiographer via intercom during the scan. You must lie very still throughout to ensure good quality images.
A CT scan takes around 10-30 minutes depending on the information required and the area of the body being scanned.
A CT scan is completely painless. People with severe claustrophobia might find it uncomfortable. Let your radiographer know beforehand if you think you might find it difficult.
CT scanning uses more X-rays than a conventional X-ray, so you are exposed to a very small amount of radiation. This is highly unlikely to cause any long-term harm. However, pregnant women should not have a CT scan unless absolutely necessary. Young children are at greater risk than adults so again, the procedure is recommended only if they have a serious condition.
The differences between a CT and an MRI scan are that CT scanning uses X-ray, which causes exposure to a small amount of radiation, whereas an MRI scan uses a magnetic field. An MRI unit will surround the entire body. A CT scanner is a doughnut shaped ring that passes around the body. Generally an MRI scan will take longer.