X-rays, like visible light, are a form of energy on the electromagnetic spectrum. Just as light makes an image on photographic film (or a digital camera sensor), X-rays can also form an image. The difference is that energetic X-rays can penetrate bone and soft tissue, and reveal its hidden structure by their varying degrees of absorption; in other words, they form a grayscale picture of what’s underneath the surface. But conventional X-rays are limited: Like a still-life picture, they show only one perspective on the scene.
Now imagine a “flip book” — the kind of small book made up of a series of pictures, each slightly different. When you rapidly page through it, you may see (for example) an animated cartoon or a still subject from different perspectives. If you could put together a flip book made from a series of X-ray “slices” of the same subject, taken at slightly different angles, you would be able to create an “animation” of the X-rays. And from there, it’s only one more step to making a 3-D model.
That’s exactly what CBCT scanners do. Using a rotating imaging device that moves around the patient’s head, the scanner records between 150 and 600 different X-ray views in under a minute. Then, a powerful computer processes the information and creates a virtual model of the area under study. When it’s done, the model appears like a three-dimensional image on a computer screen: It can be rotated from side to side or up and down, examined in greater or less detail, and manipulated in any number of ways — all without the patient feeling any discomfort. or even being present.