What Is A B-scan?

The B-scan technique produces a two dimensional picture of a cross-section of the body. Two types of B-scanner are currently in common use; we shall describe just one of these- the linear array scanner. This consists of a line of about 100 transducers that are triggered one after another in rapid succession. Each transducer detects the echoes from the various interfaces directly in the line with it, and each echo gives rise to a bright spot on the display. The brightness of the spot is determined by the amplitude of the echo. Its position on the screen corresponds to the point in the body that produced the echo. This is achieved by relating the y-component of the position of the spot to the time interval between transmission and reception of the pulse, and the x-component to the position of the particular transducer that produces it. The images are produced in such rapid succession that the picture is created almost instantaneously, and a whole series of complete pictures can be produced one after another (about 25 time per second) to create a "real time", moving image. The earliest types of B-scanner had only a single transducer and this was moved across the surface of the body by the operator.

This technique gives a two dimensional view of a cross-section of the body. This is a term used in ophthalmology.