A new wire phantom for accurate measurement of acoustical resolution

This article describes a phantom which is easier to use and gives more accurate results than a phantom made from several pairs of solid wires. This phantom employs two concepts: spatially modulated wires and diverging wires. Spatially modulated wires, such as helically twisted wires, reflect the sound into a broad range of angles. This has two advantages. One, it is easier to align the transducer with the reflected beam. Two, the diffuse reflection is similar to the scattering from tissue, and the system gain need not be turned abnormally low. Diverging wires improve the accuracy and convenience of the measurement. Rather than many pairs of parallel wires, a single pair of wires which diverge from an apex is used. By scanning across this pair until the wires are just resolved, the resolution can be easily calculated.