What is a CAT scan?

Answer 1

A type of X-ray where they use a computer to create a three-dimensional picture of the body part. CAT stands for Computerized Axial Tomography.

Tomography is complicated to explain but basically it was discovered if you move the x-ray plate and the x-ray tube at the same time while making a radiographic exposure depending on where you put the fulcrum you can create and x-ray that looks at a specific level inside the body.

You can decide you need to see the level of the patient 1 cm, 2 cm 3 cm or so on and the x-ray will be an image that displays only the most detail that many centimeters deep into the patient's body. This was predominantly done for x-raying the kidneys or tumors. So you would measure the patient's body thickness then determine by measurements assigned to the fulcrum, by the x-ray machine manufacturer, where to set the fulcrum in order to make a tomogram thick enough to display the area you want to see.

So the x-ray machine while exposing would be moving from head to toe above the patient while the x-ray plate moved in sync with it so that the x-ray beams are hitting the plate the entire time it travels. So if the x-ray tube was at the head of the patient at the start of the exposure the rod attached from it to the plate would put the plate at the opposite end near the patient's feet. As the x-ray tube moved toward the patient's feet the plate under the patient would move toward the patient's head.

This type of tomogram is a coronal cut from the front of the body to the back.

The CAT scan was developed with different approach in that the x-ray tube would travel around the body of the patient like a hula hoop as it goes around the body and shoots x-rays through the patient from left to right in a circle. The x-rays are not shot onto a plate with film as regular tomograms but was instead sent to a computer sensor that does a better job of taking the data given to it by the x-ray beam and assigning a pixel value from black to white of the areas inside that circle.

This image takes a picture of all the internal structures of the patient with much greater detail than previous topograms. So the images of the patient look like you have made slices like a loaf of bread. So the images are referred to as slices. Viewing the body this way is known as an axial view. So the fact that it is a type of tomogram and the fact that it was put together by the computer, and adding the fact that it is an axial cut gives you CAT Computed Axial Tomography.

Interesting enough most facilities call them CT scans now taking out the A for axial. Even though the images are shot axial just as I described, the software on computers allows the scanner to stack the slices then by doing vast amounts of mathematical equations on the data it collected it can reconstruct images that are Coronal (slices that look like the start from the front of the patient to the back), as well as Sagittal (cuts from right to left of the body)