CT Scans

Source: MedlinePlus Health Topics, U.S. National Library of Medicine

Last synced 8/10/2026Status: primary verified

What is a CT scan? Computed tomography (CT) is a type of medical imaging test that uses special x-ray equipment to make detailed pictures of the inside of your body. A CT scan produces cross-sectional pictures, which are like slices of the body. These images show the size and structure of organs, bones, and other tissues. CT images can also be combined to create 3-dimensional (3D) views. Health care providers use CT scans to diagnose, treat, and monitor many health conditions. Who needs a CT scan? Your provider may suggest a CT scan for many reasons, including: Fractures (broken bones) Cancer Tumors or masses Blood clots Signs of heart disease Spinal conditions Lung disease CT scans may also be used to find the best place to perform a biopsy or help guide certain treatments. They may also be used to check for internal bleeding or injury after trauma or to evaluate the brain for certain conditions. How do you prepare for a CT scan? You may be asked not to eat or drink for a few hours before the scan. Ask your provider if there are any special instructions to follow. For some CT scans, you may receive a contrast material. Contrast helps certain parts of the body show up more clearly on the images. Depending on what area is being examined, contrast material might be given as: A liquid to swallow A shot (injection) An enema (placed into the rectum) CT scans use ionizing radiation at levels higher than a standard x-ray, but the amount is kept as low as possible. Always tell your provider if you are pregnant or think you may be pregnant. How is a CT scan done? You may be asked to change clothes and remove jewelry or other items that could interfere with the scan. During the scan, you lie still on a table. The table slowly passes through the center of a large donut-shaped machine. The x-ray tube rotates around your body to create images. You may hear whirring sounds during the scan. You may be asked to hold your breath for short periods. The test is painless. The scan usua

Educational only

This information is for general education and is not medical advice. Always talk to a licensed U.S. clinician about your situation, medications, or treatment decisions.