ECO 2 Ultrasound Diagnostic System
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Cavitation is more likely to occur at high pressures and low frequencies in pulse ultrasound wave
in the tissue, which contains the bubble or air pocket (for instance, the lung, intestine, or scan with
gas contrast agents). The threshold under optimum conditions of pulsed ultrasound is predicted by
the ration of the peak pressure to the square root of the frequency.
MI = Pr’ / sqrt(fc)
Pr’ is the de-rated (0.3) peak rare-fractional pressure in Mpa at the point where PII is the maximum,
and fc is the center frequency in MHz. PII is the Pulse Intensity Integral that the total energy per
unit area carried by the wave during the time duration of the pulse. The peak rare- fractional
pressure is measured in hydrophone maximum negative voltage normalized by the hydrophone
calibration parameter.
Display Guideline:
For different operation modes, different indices must be displayed. However, only one index needs
to be shown at a time. Display is not required if maximum MI is less than 1.0 for any setting of the
operating mode, or if maximum TI is less than 1.0 for any setting of the operating mode. For TI, if
the TIS and TIB are both greater than 1.0, the scanners need not be capable of displaying both
indices simultaneously. If the index falls below 0.4, no display is needed. The display increments
are no greater than 0.2 for index value less than one and no greater than 1.0 for index values
greater than one (e.g. 0.4, 0.6, 0.8, 1, 2, and 3).
Display and Report
Located on the upper middle section of the system display monitor, the acoustic output display
provides the operator with real-time indication of acoustic levels being generated by the system.
For Scan
Only display and report MI, and start from 0.4 if maximum MI > 1.0, display in increments of 0.2.
Below is a simple guideline for the user when TI exceeds one limit exposure time to 4(6-TI)
minutes based on the ‘National Council on Radiation Protection. Exposure Criteria for Medical
Diagnostic Ultrasound: I. Criteria Based on Thermal Mechanisms. Report No.113 1992’.
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