Radiation Force Balance for Diagnostic and Therapeutic Medical Ultrasound
Ultrasonic power is a primary acoustic quantity and its measurement is required by international standards for both diagnostic and therapeutic ultrasound systems. The ability to measure ultrasonic power accurately is vital to ensuring the correct operation and safe use of ultrasound in medicine.
A Radiation Force Balance (RFB) provides a means to directly measure the power produced by a source of ultrasound. It accomplishes this by means of a highly accurate micro-balance that is used to determine the acoustic radiation force that occurs when ultrasound is incident upon a highly absorbing target. The RFB from Precision Acoustics Ltd can be used to measure ultrasonic power from 10 mW to 100 W over a wide range of frequencies.
Degassed water is recommended for all RFB measurements to minimise artefacts arising from bubble formation in the presence of high power fields. This is particularly important for the measurement of HIFU/HITU fields. RFB tanks can be supplied with in-out hose connections to the suspended target tank on request. Precision Acoustics Ltd can also supply water treatment systems if required.
Features of Radiation Force Balance include:
- Two suspended target configurations:
- High frequency target
- Low frequency target
- Integrated draft enclosure to minimise environmental artefacts
- Customisable configuration (on request) to accommodate unusual transducer geometries
- Automatic calculation of ultrasonic power and measurement uncertainty via bespoke software
- Automatic calculation of focussing and absorption correction factors as specified in IEC 61161 within software
- Typical type A (random) measurement uncertainties of 1% at powers >100 mW
Full Range RFB Specifications:
Precision Acoustics RFB’s (High and low frequencies) are highly specified models suitable for the majority of medical diagnostic and physiotherapy ultrasound equipment: Using the suspended target the power generated by HIFU transducers can be measured.
|High frequency||Low frequency|
|Max transducer diameter||100mm||150mm|
|Power range||10 mW – 100 W||10 mW – 50 W|
|Volume of water required||3.5 litres||17.5 litres|
|Measurement uncertainty||± 7% at 95% confidence level for powers > 50 mW|
|Frequency range||1 MHz – 20 MHz||200 kHz – 1.50 MHz|
- Calibration at 1 MHz and 3 MHz, Powers: 0.1 W, 0.5 W, 1 W, 5 W and 10 W.
- Calibration at single frequency at Powers to be agreed.
- Calibration at 1 MHz and 3 MHz, Powers: 0.1 W, 0.5 W, 1 W, 5 W and 10 W AND 3 Outputs in the range 10 mW to 1 W at 0.928 MHz and 3.151 MHz AND 2 Outputs in the range 10 mW to 200 mW at 5.287 MHz and 7.415 MHz and 9.541 MHz.