User guide

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Even when MI is less than 1.0, the system provides a continuous real-time display of MI in all
imaging modes, in increments of 0.1.
The system meets the output display standard for TI and provides a continuous real-time display of
TI in all imaging modes, in increments of 0.1.
The TI consists of three user-selectable indices, and only one of these is displayed at any one time.
In order to display TI properly and meet the ALARA principle, the user selects an appropriate TI
based on the specific exam being performed. SonoSite provides a copy of
AIUM Medical Ultrasound
Safety
, which contains guidance on determining which TI is appropriate (See “Related guidance
documents” on page 125).
MI and TI output display accuracy
The accuracy result for the MI is stated statistically. With 95% confidence, 95% of the measured MI
values will be within +18% to -25% of the displayed MI value, or +0.2 of the displayed value,
whichever value is larger.
The accuracy result for the TI is stated statistically. With 95% confidence, 95% of the measured TI
values will be within +21% to -40% of the displayed TI value, or +0.2 of the displayed value,
whichever value is larger. The values equate to +1dB to -3dB.
A displayed value of 0.0 for MI or TI means that the calculated estimate for the index is less than
0.05.
Factors that contribute to display uncertainty
The net uncertainty of the displayed indices is derived by combining the quantified uncertainty from
three sources: measurement uncertainty, system and transducer variability, and engineering
assumptions and approximations made when calculating the display values.
Measurement errors of the acoustic parameters when taking the reference data are the major
source of error that contributes to the display uncertainty. The measurement error is described in
“Acoustic measurement precision and uncertainty” on page 164.
P21x/5-1 MI Yes Yes Yes No
TIC, TIB, or TIS Yes Yes Yes Yes
SLAx/13-6 MI No No No —
TIC, TIB, or TIS No No Yes —
TEEx/8-3 MI No No No No
TIC, TIB, or TIS No No Yes Yes
Table 3: TI or MI  1.0 (continued)
Transducer Model Index
2D/
MMode
CPD/
Color
PW
Doppler
CW
Doppler