User's Manual

Rev.1.01
2022. 03.
42 / 57
Doc # : BN-SF-EOP-01
attenuation coefficient, choosing conservative values of tissue characteristic.
Therefore, displayed MI and TI values should be relative information for reference,
they serve to indicate to the operator whether a particular setting of the system
increases or decreases the possibility of Thermal or Mechanical effect, used to help
the operator be careful to use ultrasonic diagnostic system and follow the ALARA
principle, these values cannot be equal to actual values.
6.2.3.3 Uncertainty of Measurement
Sound pressure is the most basic data of sound field measurement, and other sound
field parameters can be deduced from sound pressure, so when analyzing
measurement uncertainty, only take sound pressure for analysis and uncertainty of
other parameters can be deduced from the sound pressure.
Measurement uncertainty mainly include repeated measurement uncertainty and the
system uncertainty, the system uncertainty is an order of magnitude higher than
repeated measurement uncertainty, so the main analysis is the system uncertainty.
Mainly decided by the following factors:
1) The sensitivity of hydrophone: According to hydrophone calibration report
provided by ONDA company, the maximum allowable error of sound pressure for
hydrophone is ±12%
2) Scope: according to Agilent DSO6502A specifications, its effect on the sound
pressure is ±2%
3) Temperature: effect of the thermocouple on sound pressure error is ±4%
Above all uncertainty components are not related, synthetic standard uncertainty of sound
pressure is ±13%
6.2.3.4 Operator Control Property
There are several system controls that the operator can use to adjust the image
quality and limit the acoustic intensity. These controls are related to the techniques
that an operator might use to implement ALARA and can be divided into three
categories: direct, indirect, and receiver controls