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Appendix A Acoustic Output Data
A.1 Description
Acoustic output
The acoustic output display is located at the top right corner of the system display
Note:
1.
If either MI or TI displays a value greater than 1.0, please follow the ALARA guidelines carefully.
2. The sound intensity parameters usually generated by the ultrasonic probe and their meanings are
described as follows:
Mechanical index
The mechanical index can be defined as the peak expansion pressure (MPa)
(determined by the tissue attenuation coefficient of 0.3 dB / cm / MHz) divided by the
square root (MHz) of the probe center frequency.
Thermal sensitivity
The thermal index (TI) is the ratio of power required to assess soft tissue or bone
temperature rise by 1 °C.
Peak expansion pressure
The peak expansion pressure (in MPa) is the temporary peak expansion pressure at
the specified point.
Pulse intensity integral
The pulse intensity integral is the instantaneous rate-time integral of any given point
and any specified pulse in which the audio pressure or the underwater audio signal is
included in a non-zero region. Each pulse is equal to the energy density Joule.
A.2 Maximum probe surface temperature
Subject to Section 42.3 of the standard, the maximum surface temperature data of the
probe used in this system are measured in two environments: placing the probe in static air