Choice of moving target for a string phantom: II. On the performance testing of Doppler ultrasound systems.

A string phantom was used to test a duplex system using several filaments: braided silk, nylon and O-ring rubber. The estimated pulsatility index was identical for all filaments tested. Range gate registration measurements were identical for all filaments tested. Maximum velocity was underestimated in the region of a strong angular backscatter peak; this was the case for several of the braided silk filaments. This effect was not observed for O-ring rubber. The paper concluded that O-ring rubber is a suitable filament for the testing of several key Doppler quantities. Recalibration of the string phantom velocity indicator is necessary due to the large diameter of the O-ring rubber.