Typical Number in Hospital: 1 Cost Bands: 2 References: 1

This is a device for testing the performance of ultrasonic scanners and consists of two parallel plates of Perspex between which there are a number of steel or nylon threads. It may be a closed system containing a fluid with a velocity of sound transmission equal to that of tissue (usually 1540 m/s) or it may be an open frame intended to be immersed in a bath of suitable fluid. This fluid can be a special mixture of ethyl alcohol in water at room temperature or water may be warmed to 47[d]C at which the transmission velocity is correct.

There are four rows of wires in the frame as follows:

1. A row of equally spaced wires down the frame to give an indication of variation of the ultrasonic beam width with depth, and also of sensitivity with depth.

2. A row of wires across the frame at the bottom.

3. A row of wires across the frame close to the transducer which are spaced equally but each successive wire is slightly further away from the transducer. These indicate the depth of the transmit artefact or deadzone due to the ringing of the transducer after the transmit pulse has been sent.

4. A row of wires moving progressively away from the transducer position which have progressively smaller spaces between them to demonstrate axial resolution.

The AIUM is the American Institute for Ultrasound in Medicine.

Content and Design Copyright 2000 Dr. Malcolm C Brown.  See Title Page for more details