What is CT Imaging?

Nicole Madison
Nicole Madison

Computed tomography (CT) imaging, also referred to as a computed axial tomography (CAT) scan, involves the use of rotating x-ray equipment, combined with a digital computer, to obtain images of the body. Using CT imaging, cross sectional images of body organs and tissues can be produced. Though there are many other imaging techniques, this form has the unique ability to offer clear images of different types of tissue. It can provide views of soft tissue, bone, muscle, and blood vessels, without sacrificing clarity. Other imaging techniques are much more limited in the types of images they can provide.

CT imaging helps to provide images of internal organs.
CT imaging helps to provide images of internal organs.

To understand the difference between CT imaging and other techniques, consider an x-ray of the head. Using basic x-ray techniques, the bone structures of the skull can be viewed. With magnetic resonance imaging (MRI), blood vessels and soft tissue can be viewed, but clear, detailed images of bony structures cannot be obtained. On the other hand, x-ray angiography can provide a look at the blood vessels of the head, but not soft tissue. A CT of the head can provide clear images not only of soft tissue, but also of bones and blood vessels.

Doctors rely on CT images for diagnosis.
Doctors rely on CT images for diagnosis.

CT imaging is commonly used for diagnostic purposes. In fact, it is a chief imaging method used in diagnosing a variety of cancers, including those affecting the lungs, pancreas, and liver. Using this type of imaging, not only can medical professionals confirm that tumors exist, but they can also pinpoint their locations, accurately measure the size of tumors, and determine whether or not they’ve spread to neighboring tissues.

CT imaging produces a cross section of the body, including soft tissue and body organs.
CT imaging produces a cross section of the body, including soft tissue and body organs.

In addition to the diagnosis of certain cancers, a CT can be used for planning and administering radiation cancer treatments, as well as for planning certain types of surgeries. It is useful for guiding biopsies and a range of other procedures categorized as minimally invasive. Thanks to its ability to provide clear images of bone, muscle, and blood vessels, it is a valuable tool for the diagnosis and treatment of musculoskeletal disorders and injuries. It is often used to measure bone mineral density and to detect injuries to internal organs. A CT scan is even used for the diagnosis and treatment of certain vascular diseases that, undetected and untreated, have the potential to cause renal failure, stroke, or death.

An x-ray cannot provide a look at soft tissue, but can at blood vessels.
An x-ray cannot provide a look at soft tissue, but can at blood vessels.

CT imaging itself is pain-free, but some individuals may experience discomfort because they are required to lie still for a period of time. The procedure is typically performed by a well-trained CT technologist.

The CT imaging process is pain-free, but some may experience discomfort from being required to lie still for prolonged periods.
The CT imaging process is pain-free, but some may experience discomfort from being required to lie still for prolonged periods.
Nicole Madison
Nicole Madison

Nicole’s thirst for knowledge inspired her to become a wiseGEEK writer, and she focuses primarily on topics such as homeschooling, parenting, health, science, and business. When not writing or spending time with her four children, Nicole enjoys reading, camping, and going to the beach.

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Discussion Comments


@Kristee: The CT scanner still uses X-Rays and an image receptor to acquire the image. It rotates around the patient and acquires the information and then converts it into an image.

Contrast can be used and is administered a few different ways (IV, orally etc) depending on the examination. Sometimes however, no contrast is needed. It depends on what we are looking for.


@Kristee – I had to drink a barium shake. It had a chalky texture, but at least it was fruit flavored. That made it bearable.

Some people have to have the contrast dye injected through an IV. It all depends on what they will be looking at during the scan.

Even though the shake wasn't enjoyable, I would much rather drink it than have to have something injected into my vein. I hate needles, and I'm glad I had this option.


What makes the images show up on the scan? Do you have to take some sort of contrast dye, or is there some other trick to this?


I've always heard these x-rays referred to as “catscans.” I had to have one after going through a couple of weeks of excruciating abdominal pain.

My doctor suspected that the problem was in my intestines, but the CT showed that I actually had multiple cysts on my kidneys. She diagnosed me with polycystic kidney disease.

I'm glad that the CT was able to show this, even though she didn't know to look for it in the first place. The rest of my family was able to get tested, since this is a genetic condition.


@ceilingcat- I'm in the medical field and I can tell you most doctors don't order an imaging diagnostic based on the cost. Usually they order it based on what they need to make a diagnosis.

However, this can end up hurting the patient financially if their insurance company won't cover the scan for some reason.


@Monika- I have to have some CT scans done soon and I'm sure I'm going to be as uncomfortable as you were! I'm relieved to know it's not going to actually hurt though. In fact after reading this article I'm actually kind of looking forward to it. It sounds so interesting.

I'm glad I have good insurance because I've heard CT scans are actually more expensive than x-rays or ultrasounds. I wonder if this means doctors order them for their patients less?


I had some cardiac CT imaging done and like the article said it didn't hurt but it felt like it took forever! I'm sure I lie still on my couch at home all the time when I watch tv but not being able to move is a totally different story. It seemed like every ten seconds I had a new itch that I couldn't scratch!

The discomfort was totally worth it though. I got to look at a neat picture of my heart and also got a clean bill of health.

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