A B – scan is taken by building up an image from many different A – scans. The ultrasound transducer is moved across the patients body in the area of interest, it's position and orientation being constantly monitored by having sensors attached. Each reflected pulse is analysed to find the depth and nature of the reflecting surface. A two dimensional image is built up on a screen from dots, with the position of the dot representing the positio of the reflecting surface and the brightness of the dot indicating the intensity of the reflection.
Because a B – scan is built up over a period of time, the image will be blurred if the imaged organ is moving – if it is a beating heart for example. The image below is a B – scan of the area around the optic nerve.
