or caused by measuring according to, the AIUM measurement standards, or the
effects of nonlinear 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 output power control is adjusted; but other system
controls affect the on-screen output values.
Power
The output power control affects the system acoustic output. Two real-time
output values are on the display: TI and MI. They change as the system responds
to power-control adjustments.
In combined modes, such as simultaneous Color, 2D, and PW 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
peak pressure.
2D Controls
• Sector Width: Narrowing the sector angle may increase frame rate. This
action will increase the TI. Pulser voltage may be automatically adjusted
down with software controls to keep the TI below the system maximums.
A decrease in pulser voltage will decrease MI.
• Zoom: Increasing the zoom magnification by pressing Zoom may increase
frame rate. This action will increase the TI. The number of focal zones may
also increase automatically to improve resolution. This action may change
the MI, because the peak MI can occur at a different depth.
• Number of Focal Zones: More focal zones may change both the TI and
MI by changing frame rate or focal depth automatically. Lower frame rates
decrease the TI. MI displayed will correspond to the zone with the largest
MI value.
iU22 User Manual
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Safety
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