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CT Scans

One of the most common ways to capture internal body images is with a computed tomography (CT) scan.

CT scans, also called CAT scans, use a rotating X-ray machine to create cross-sectional, or 3D, images of any body part, according to the National Institute of Biomedical Imaging and Bioengineering (NIBIB). They provide a painless, noninvasive and fast way for doctors to examine bones, organs and other internal tissues.

How CT scans work?

During a CT scan, the patient lies on a table that moves through a doughnut-like ring known as a gantry, according to the NIBIB. The gantry has an X-ray tube that rotates around the patient while shooting narrow beams of X-rays through the body. The X-rays are picked up by digital detectors directly opposite the source.

After the X-ray source completes a full rotation, a sophisticated computer creates a 2D image of that slice of the body, which typically ranges from 0.04 to 0.4 inches (1 to 10 millimeters) thick. The computer then combines several 2D slices to create a 3D image of the body, making it easier for a doctor to pinpoint where the patient's problem exists. The scan itself typically takes less than 15 minutes depending on the area of the body being imaged.

To make it easier to identify abnormalities, the patient may be given a contrast material. Solutions containing contrast materials, such as iodineor barium, are introduced into the body orally, rectally or injected directly into the bloodstream, depending on the target tissue. The materials in the solution work by temporarily altering how X-rays interact with certain body tissues, which makes those tissues appear different in the resulting image

Why get a CT Scan?

CT scan images help doctors diagnose and pinpoint infections, muscle disorders, bone fractures, cancer, tumors and other abnormalities.

In emergency situations, CT scans are life-saving tools that allow doctors to quickly determine the extent of internal injuries or internal bleeding, according to the Radiological Society of North America.

CT scans are also vital in cancer diagnosis, treatment and research, according to the National Cancer Institute.

Risks involved

Depending on the area of the body being scanned, there may be risk of radiation exposure, according to the American College of Radiology Imaging Network (ACRIN). X-rays are a source of ionizing radiation, which can damage sensitive tissues such as lymphoid organs and blood. CT scans around the abdomen are not advised for pregnant women because of a chance the fetus would be exposed to harmful radiation.

More time in the CT scanner may lead to higher-quality images but also a higher radiation dose, which is often unnecessary, said Dr. Phuong-Anh Duong, director of computed tomography and associate professor at Emory University Department of Radiology and Imaging Sciences in Georgia.

Next-generation CT scanners

Artificial intelligence (AI) is being incorporated into CT scanners to create better images with less radiation, Duong told Live Science.

Earlier this year, researchers at the University of Central Florida incorporated AI into a CT scan system that was able to detect trace amounts of lung cancer.

Another big leap forward in CT scan technology are photon-counting CT scanners. These scanners incorporate a detector that counts and tracks individual photons from the X-ray source and detects individual photon interactions. The result is a clearer image with improved resolution and contrast, as opposed to traditional CT scan images that use energy-integrating detectors to detect large numbers of photons at a time and simply measure intensity. The photon-counting CT scanners can lead to decreased X-ray doses, better tissue differentiation, sharper image quality and a reduced need for contrast material, Duong said.

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