A new phantom for quality assurance of color-coded ultrasound equipment

Color Doppler Ultrasound imaging is now routine in clinical use for evaluation of blood flow in vessels. Several phantoms and test objects are available on the market for Quality Assurance programs on color coded flow equipment but none of them allows the measurement of the spatial resolution of a color image system. A new phantom and measurement procedure for the assessment of the color spatial resolution is proposed. Various accessories can be inserted into an adapted plexiglas box, permitting the reproduction of two opposed parallel flows of synthetic blood. The box is then filled with a tissue mimicking solution. Measured flows were generated using a pump, a potentiometer and a flowmeter. It is possible to modify the liquid flow, the diameter of the simulated blood vessels, their inter-axial distance and their depth below the surface of the phantom. The apparatus measures the minimum inter-axial distance at which opposed flows can be color-resolved as a function of the flow velocity and the diameter of the vessels. Results concerning measurements on three commercial devices are presented and their different characteristics are reported.