
5-5
Chapter 5 Measurements and Calculations
Optimization of Measurement Accuracy
2D Mode
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Resolution is in proportion to the frequency of the probe.
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Penetration is in inverse proportion to the frequency of the probe.
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The highest resolution can be obtained at the focus of the probe where the ultrasound beam is
narrowest.
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The most accurate measurements can be obtained at the focus depth. The accuracy decreases as the
distance from the focus increases, widening the beam width.
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Using the zoom function or minimizing the depth display makes distance or area measurements
more accurate.
M Mode
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The accuracy of time measurements can be increased when the speed and the display format are set
to high values.
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The accuracy of distance measurements can be increased when the display format is set to higher
values.
Doppler Mode
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It is recommended to use lower frequency ultrasound for measurement of faster blood ows.
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The size of the sample volume is limited by the axial direction of the ultrasound.
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Using lower frequency ultrasound increases penetration.
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The accuracy of time measurements can be increased when the speed is increased.
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The accuracy of velocity measurements can be increased when the vertical scale is set to smaller
values.
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It is most important to use an optimal Doppler angle to enhance the accuracy of velocity
measurements.
Color/Power Doppler Mode
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A protocol is not specied for images in Color Doppler Mode or Power Doppler Mode. Therefore, the
same limitations imposed when measurements are taken in B/W images apply to the accuracy of the
measurements taken in these modes.
I want to learn how to do angle correction on PW Doppler on my machine.
How do I assess PW angle cursor?
I don't want to join the group.