The output of pulse-echo ultrasound equipment: a survey of powers, pressures and intensities

TLDR

The study surveys the powers, pressures, and intensities produced by clinical ultrasonic pulse‑echo equipment. Measurements were taken on 22 transducers (2.25–7.5 MHz) across 38 focused fields, using a calibrated force balance and PVdF hydrophone, at maximum and lower power settings and all available focus positions. Maximum powers ranged from 0.5 to 80 mW, spatial‑average temporal‑peak positive pressures from 30 kPa to 1.15 MPa, and spatial‑peak pulse‑average intensities from 3.6 × 10³ to 1.1 × 10⁷ W m⁻².

Abstract

A survey of the powers, pressures and intensities generated by ultrasonic pulse-echo equipment in clinical use has been carried out. Thre conventional B-scanners, four linear-array scanners and four mechanically sectored scanners were included in the study. Measurements were made on a total of 22 transducers covering the nominal frequency range 2.25–7.5 MHz. On those instruments where an output power control was provided, two measurements were made: one at the maximum available power and a second at a lower power. On arrays with a variable transmit focus control, measurements were made at all available focussettings. In all, measurements were made on 38 separate focused pulsedultrasonic fields. The measurements were carried out using a calibrated ultrasonic force balance, and a calibrated polyvinylidene difiuoride (PVdF) membrane hydrophone. A very wide range of maximum powers, pressures and intensities were found. Powers from 0.5–80 mW were measured; spatialaverage temporal-peak positive pressures at the transducer varied between 30 kPa and 1.15 MPa, and spatial-peak pulseaverage intensities were in the range 3.6 × 103– 1.1 × 107 Wm−2.