A river begins at a source (or more often several sources), follows a path called a course, and ends at a mouth or mouths. The water in a river is usually confined to a channel, made up of a stream bed between banks. In larger rivers there is often also a wider floodplain shaped by flood-waters over-topping the channel.
A 'computerized tomography' (CT) (or 'computerized axial tomography' (CAT) scan) uses a computer that takes data from several X-ray images of structures inside a human's or animal's body and converts them into pictures on a monitor.
CT stands for computerised tomography. A CT scan, also known as a CAT scan, is a specialised X-ray test. It can give quite clear pictures of the inside of your body. In particular, it can give good pictures of soft tissues of the body which do not show on ordinary X-ray pictures. Note: the information below is a general guide only.