Safety
HD11 XE Getting Started
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others, differences in hydrophone calibration and performance, positioning, align-
ment, and digitization tolerances, and variability among test operators.
The conservative assumptions of the output estimation algorithms of linear prop-
agation, at all depths, through a 0.3 dB/cm-MHz attenuative medium is not consid-
ered in the accuracy estimate for the display. Neither linear propagation, nor
uniform attenuation at the 0.3 dB/cm-MHz rate, occur in water tank measure-
ments or in most tissue paths in the body. In the body, different tissues and organs
have dissimilar attenuation characteristics. In water, there is almost no attenua-
tion. In the body, and in particular, in water tank measurements, non-linear propa-
gation and saturation losses occur as pulser voltages increase.
Therefore, the display accuracy estimates are based on the variability range of
transducers and systems, inherent acoustic output modeling errors, and measure-
ment variability. Display accuracy estimates are not based on errors in, or caused
by measuring according to, the AIUM measurement standards, or the effects of
non-linear loss on the measured values.
Control Effects
Controls Affecting the Indices
As various system controls are adjusted, the TI and MI values may change. This
will be most apparent as the Power control is adjusted; however, other system
controls will affect the on-screen output values.
Power
Power controls the system acoustic output. Two real-time output values are on
the screen: a TI and MI. They change as the system responds to Power adjust-
ments.
In combined modes, such as Triplex (simultaneous Color, 2D, and pulsed-wave
Doppler), the individual modes each add to the total TI. One mode will be the
dominant contributor to this total. The displayed MI will be from the mode with
the largest MI value.
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