Scientists Say: CT scan

This technology gives us a peek inside the body, no cutting required


These are CT scan images of the human brain.


CT scan (noun, “SEE TEE scan,” or CAT scan “CAT scan”)

The “CT” in a CT scan is an abbreviation. It’s for “computed tomography” or “computerized axial tomography” (which is abbreviated “CAT scan”). Doctors and scientists can use this technology to look inside something, without having to cut it. To make a CT scan, a person or an object is placed in a circular scanner. Inside the scanner is a machine that generates X-rays, a type of radiation. The machine uses the X-rays to take photos from every angle around the person or object. Then a computer combines the pictures. The result is a set of three-dimensional images that look like slices through the person or object. These images provide much more detail than a single X-ray. And they allow someone to look at, and through, an object from every angle. No knife required.

In a sentence

Scans of ancient pterosaur eggs using CT scans revealed babies fossilized inside. 

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Bethany Brookshire was a longtime staff writer at Science News Explores and is the author of the book Pests: How Humans Create Animal Villains. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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