In-situ Attenuation Corrections for Radiation Force Measurements of High Frequency Ultrasound With a Conical Target.

Radiation force balance (RFB) measurements of time-averaged, spatially-integrated ultrasound power transmitted into a reflectionless water load are based on measurements of the power received by the RFB target. When conical targets are used to intercept the output of collimated, circularly symmetric ultrasound sources operating at frequencies above a few megahertz, the correction for in-situ attenuation is significant, and differs significantly from predictions for idealized circumstances. Empirical attenuation correction factors for a 45° (half-angle) absorptive conical RFB target have been determined for 24 frequencies covering the 5 MHz to 30 MHz range. They agree well with previously unpublished attenuation calibration factors determined in 1994 for a similar target.