Quatech Audio/Video Capture USB 2.0 Spécifications télécharger pdf (Page 255)

z.one ultra and z.one ultra sp OPERATOR MANUAL 9-53

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These accuracy statements are consistent with PW elapsed time measurement

tests performed using a CIRS Model 43 String Phantom with distilled water as the

fluid medium.

Color Doppler

Velocity

Measurement

Accuracy

Factors that limit the accuracy of velocity measurements in Color Doppler (CD)

include the finite sample volume size and short period of sample volume

interrogation. In addition, z.one systems may use different CD frequencies at

different maximum depth of the CD box. Therefore, CD is not intended for making

quantitative clinical measurements. Rather, CD should be used as an adjunct to

quantitative techniques, allowing the user to search for the regions of interest and

observe the flow dynamics in those regions.

Velocity

Accuracy in

The best L10-5 CD velocity accuracy that has been achieved using a Gammex

Model 1425A Doppler Flow Phantom is ±15% relative to the calculated velocity at

the center of the 5-mm inner diameter flow tube, for volume flow rates from

0.5-1.0 meters/sec with a Doppler angle of 50°, and with a CD box of 40 mm

maximum depth. However, due to the fundamental limitations of CD accuracy,

larger mean velocity errors can be expected at other CD box depths and Doppler

angles.

Table 9-7. PW Strip: Scan Engine Displays

Sweep Speed

(pixels/sec)

Sweep Speed

(sec)

Error in

Measurement (1.0

sec)

360 1.4 0.4%

180 2.7 0.8%

120 4.1 1.3%

90 5.4 1.7%

60 8.1 2.5%

Table 9-8. PW Strip: SmartCart/SmartCart sp Display

Sweep Speed

(pixels/sec)

Sweep Speed

(sec)

Error in

Measurement (1.0

sec)

360 1.9 0.2%

240 2.8 0.6%

180 3.7 0.8%

120 5.6 1.3%

90 7.5 1.7%

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