A computed tomography scan (CT scan) uses computers and rotating X-ray machines to create cross-sectional images of the body, taking a series of X-rays from different angles. These images provide more detailed information than normal X-ray images as they create slices or cross-sections of the body. They may also be combined to produce a 3D image of a particular area of the body. They can show the soft tissues, blood vessels and bones in various parts of the body.
How is it performed?
- Before the scan begins, the patient is asked to change into a hospital gown and all metal objects, like jewellery, dentures and so on, must be removed.
- While performing the scan, it is important that the patient lies still in order to obtain the clearest images. If they are unable to do so, a mild sedative might be given.
- The patient lies down on a table that slides into the CT machine.
- Once the scan begins, the table slides slowly into the scanner while the X-ray machine rotates around the table. Each rotation produces numerous images of thin slices of the patient’s body.
- A special dye called a contrast material might be administered intravenously or orally (depending on which part of the body needs to be highlighted) to help visualise internal structures. The contrast material blocks X-rays and appears white on the images, allowing it to highlight the intestines, blood vessels or other structures in the area being examined.
- When in use, the machine produces clicking, buzzing and whirring. The table moves a few millimetres at a time until the exam is finished. The entire procedure may take anywhere from 20 minutes to one hour.
- Once the scan is over, the images are sent to the radiologist for examination.
- There is very little risk associated with a CT scan. Though these scans expose the patient to more radiation than typical X-rays, the risk of radiation-induced cancer is negligible.
Some people might have an allergic reaction to the contrast material.