The acronyms CAT scan and CT scan often cause confusion for patients trying to understand an upcoming medical imaging procedure. While the names appear different, they both refer to the exact same diagnostic technology, a powerful tool that uses X-rays and computer processing to look inside the body. This article clarifies the reasons behind the dual naming convention, explains how this technology works, and details what a patient experiences during the test.
Resolving the Terminology Confusion
The terms CAT scan and CT scan describe the identical medical imaging technique, though the full names have slightly different roots. The original term was CAT scan, which stood for “Computerized Axial Tomography.” This name highlighted the technology’s ability to create cross-sectional images, or “slices,” primarily along the body’s horizontal axis (the axial plane).
As the technology improved, the machinery became sophisticated enough to reconstruct images in multiple planes, including coronal (front-to-back) and sagittal (side-to-side) views. Because the technology was no longer limited to just the axial plane, the term was simplified to CT scan, standing for “Computed Tomography.” Although CT scan is the more modern and accurate term, the older name, CAT scan, is still commonly used today.
The Core Technology Behind CT Scans
Computed Tomography uses a rotating array of X-ray sources and detectors housed within a large, donut-shaped machine called a gantry. Unlike a standard X-ray machine, the CT scanner rotates a narrow beam of X-rays around the patient. As the X-rays pass through the body, different tissues absorb the radiation to varying degrees, a process known as attenuation.
Detectors opposite the X-ray source measure the energy that passes through the body from hundreds of different angles. These measurements are sent to a computer, which uses mathematical techniques (tomographic reconstruction algorithms) to process the data. This processing creates a two-dimensional image representing a thin cross-sectional slice, offering greater detail of soft tissues, organs, and bones than a conventional X-ray. The computer can then digitally “stack” these slices to create a detailed three-dimensional view.
What Happens During the Procedure
The CT scan procedure is non-invasive and relatively quick, typically lasting only a few minutes once the scan begins. You lie on a motorized table that slides you into the center opening of the gantry. To ensure image clarity, you will be asked to remove metal objects, such as jewelry or belts, and may change into a hospital gown.
In some cases, a contrast agent is used to highlight specific structures like blood vessels or organs. This material may be given orally, rectally, or intravenously (IV) through a small catheter. If administered intravenously, you might feel a temporary warm sensation or a metallic taste in your mouth.
Throughout the scan, the technologist monitors you from an adjacent control room and communicates via an intercom. It is important to remain completely still while the table moves and the X-ray tube rotates. You may be instructed to hold your breath for several seconds to prevent motion blur, especially when scanning the chest or abdomen. The test itself is painless, though the machine makes clicking and whirring sounds.