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.