CT-Scans (standing for computerized tomography scans) are a series of X-ray images of an object, taken from different angles to produce cross-section images (topographies) of an object. It allows you to look inside most objects without having to cut them open, very handy in fields like medicine or security, to name a few.
They create an image by using Röntgen radiation, more widely known as X-rays — having a much higher energy than visible light, they penetrate through most materials and are captured by a special film on the other side.
They also damage living cells much in the same way as other types of radiation, but for now let’s not think of that and enjoy this strangely relaxing CT of an unopened walnut.