Chapter 2. Safety 2 – 27
■ Zoom
Increasing the zoom magnification may increase frame rate. This will increase the TI. The
number of focal zones may also increase automatically to improve the resolution. This action
may change the MI, since the peak intensity can occur at a different depth.
■ Number of Focal Zones
Increasing the number of focal zones may change both the TI and MI by automatically
changing the frame rate or focal depth. Lower frame rates decrease the TI. The MI displayed
will correspond to the focal zone with the largest peak intensity.
■ Focus
In general, higher MI values will occur when the focal depth is near the natural focus of the
probe (transducer).
2.5.1.8. Color and Power Controls
■ Color Sensitivity
Increasing the color sensitivity may increase the TI. More time is required for the scanning of
color images. Color pulses are the dominant pulse type in this mode.
■ Color Sector Width
Narrower color sector width will increase the color frame rate, and so the TI will increase.
The system may automatically decrease the pulse voltage to stay below the system
maximum. A decrease in pulse voltage will decrease the MI. If Pulsed Doppler is also
enabled, then Pulsed Doppler will remain the dominant mode and the TI change will be small.
■ Color Sector Depth
Deeper color sector depth may automatically decrease color frame rate, or select a new
color focal zone or color pulse length. The TI will change due to the combination of these
effects. Generally, the TI will decrease with increased color sector depth. MI will correspond
to the peak intensity of the dominant pulse type, which is a color pulse. However, if Pulsed
Doppler is also enabled, then Pulsed Doppler will remain the dominant mode and the TI
change will be small.
■ Scale
Using the Scale control to increase the color velocity range may increase the TI. The system
will automatically adjust the pulse voltage to stay below the system maximum. A decrease in
pulse voltage will also decrease MI.
■ 2D Mode Size
A narrower 2D mode sector width in Color imaging will increase color frame rate. The TI will
increase. MI will not change. If Pulsed Doppler is also enabled, then Pulsed Doppler will
remain the dominant mode and the TI change will be small.
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