04/10/2020
A computerized tomography (CT) or computerized axial tomography (CAT) scan combines data from several X-rays to produce a detailed image of structures inside the body.
CT scans produce 2-dimensional images of a “slice” or section of the body, but the data can also be used to construct 3-dimensional images. A CT scan can be compared to looking at one slice of bread within a whole loaf. A CT scanner emits a series of narrow beams through the human body as it moves through an arc.
This is different from an X-ray machine, which sends just one radiation beam. The CT scan produces a more detailed final picture than an X-ray image.
The CT scanner’s X-ray detector can see hundreds of different levels of density. It can see tissues within a solid organ.
This data is transmitted to a computer, which builds up a 3-D cross-sectional picture of the part of the body and displays it on the screen.
Sometimes, a contrast dye is used because it can help show certain structures more clearly.
For instance, if a 3-D image of the abdomen is required, the patient may have to drink a barium meal. The barium appears white on the scan as it travels through the digestive system.
If images lower down the body are required, such as the re**um, the patient may be given a barium e***a. If blood vessel images are the target, a contrast agent will be injected into the veins.
The accuracy and speed of CT scans may be improved with the application of spiral CT, a relatively new technology. The beam takes a spiral path during the scanning, so it gathers continuous data with no gaps between images.
CT is a useful tool for assisting diagnosis in medicine, but it is a source of ionizing radiation, and it can potentially cause cancer.
The National Cancer Institute advise patients to discuss the risks and benefits of CT scans with their doctors.
