What Are CT (CAT) Scans?

    A computed tomography scan (CT scan), also called computed axial tomography scan (CAT scan), is a type of imaging test. It uses computers and a rotating X-ray machine to take cross-sectional pictures of the body. CT scans give doctors more detailed images than X-rays can provide. Unlike X-rays, they can show organs, soft tissues, and blood vessels in addition to bones.

    CT scans are painless. A CT scan involves more exposure to radiation than a regular X-ray does, but the risk is small.

    What Is a Head CT Scan?

    A CT scan of the head uses a special X-ray machine to take pictures of the brain, skull, and sinuses, as well as blood vessels in the head.

    A person getting a CT scan lies on a table. A pillow and sometimes a soft brace will hold their head and neck in place to prevent movement that would result in a blurry image. The donut-shaped machine circles the head, taking pictures to provide cross-sections of the brain from various angles. These pictures are sent to a computer that records the images. It also can put them together to form 3D images.

    Why Are Head CT Scans Done?

    Doctors may order a head CT scan to:

    • check for conditions in the brain such as hydrocephalus, swelling, inflammation, bleeding, and signs of injury
    • check for the presence, location, and size of abscesses, cysts, and tumors
    • locate birth defects in the brain and skull
    • look at malformed or injured blood vessels in the head
    • find the cause of headaches, weakness, or a change in mental status

    What if I Have Questions?

    If you have questions about the head CT scan or what the test results mean, talk to your doctor. 

Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.
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