Radiation Force Balance for Diagnostic and Therapeutic Medical Ultrasound
Ultrasonic power is a primary acoustic quantity and its measurement is required by international specification standards for both diagnostic and therapeutic ultrasound systems. In order to comply with the US FDA 510(k) regulatory requirements, IEC61157 and IEC61689, medical equipment manufacturers are required to measure ultrasonic power. The ability to measure it accurately is vital to ensuring the correct operation and safe use of ultrasound in medicine.
Typically scanned hydrophone measurements of acoustic power have an uncertainty that is no better than 20%, whereas commercial power balances that can measure to 10%.
The Radiation Force Balance (RFB) from Precision Acoustics is a highly specified model, which is almost identical to those used within The UK National Physical Laboratory. It has been designed for the measurement of medical diagnostic and physiotherapy equipment in the frequency range 1MHz to 10MHz and the power range 10mW to 10W.
The Precision Acoustics RFB uses an ‘absorbing well' target, which allows the design to be tailored to individual requirements for frequency, power and transducer geometry. Variations on this model can be provided for use at higher or lower frequencies and powers.
The RFB can be used as a stand-alone device or connected to a PC to provide a permanent record of results in an approved Quality System.
Each RFB is supplied with:
- an absorbing target suitable for the power level to be measured
- a NPL calibration certificate, traceable directly to the UK Primary Standard for ultrasound power
- approved measurement protocol and user instructions
- software for data acquisition and analysis
- retort stand to hold the transducer under test
Full Range RFB Specification:
Precision Acoustics can supply RFB's for different applications but the specification below is for a highly specified model suitable for the majority of medical diagnostic and physiotherapy ultrasound equipment:
- frequency range 1MHz to 10MHz*
- power range (calibration range) 20mW to 10W*
- overall measurement uncertainty* -- for 50mW to 5W, less than +/-7% at 95% confidence
- For power levels greater than 100mW the typical type A (random) measurement uncertainties is typically only 1%
- maximum transducer diameter 5cm*
*The RFB may be used outside of this range with increased uncertainty levels OR it can be modified to meet specific requirements
Most modifications are inexpensive but please contact us with details of the transducer size, frequency and power range and accuracy required. We will send you a quotation for a modified RFB which will ensure that
- the RFB absorbing target will be large enough to encompass the complete acoustic beam.
- the balance has enough resolution for the accuracy required
- the RFB is calibrated over the frequency and power range that you are measuring to ensure traceable measurements.
Listed are the options available for NPL calibrations which are traceable to the UK's Primary Standard.
- calibration at 1 and 3MHz, Powers: 0.1W, 0.5W, 1W, 5W and 10W (Order Code RFB1/3)
- calibration at single frequency at Powers to be agreed (Order Code RFB 1)
- calibration at 1 and 3MHz, Powers: 0.1W, 0.5W, 1W, 5W and 10W AND 3 Outputs in the range 10mW to 1W at 0.928MHz and 3.151MHz AND 2 Outputs in the range 10mW to 200mW at 5.287MHz and 7.415MHz and 9.541MHz (Order Code RFBFULL)
Please contact us for further details.
