GE Vscan Extend, Руководство пользователя

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Appendix
7-12
Vscan Extend
–
User Manual
5721203-100 Rev. D
Measurement accuracy
Basic Measurements
The following information is intended to provide guidance to the
user in determining the amount of variation or measurement
error that should be considered when performing clinical
measurements with this equipment. Error can be contributed by
equipment limitations and improper user technique. Be sure to
follow all measurement instructions and develop uniform
measurement techniques among all users to minimize the
potential operator error. Also, in order to detect possible
equipment malfunctions that could affect measurement
accuracy, a quality assurance (QA) plan should be established
for the equipment that includes routine accuracy checks with
tissue mimicking phantoms.
Please be advised that all distance and Doppler related
measurements through tissue are dependent upon the
propagation velocity of sound within the tissue. The propagation
velocity usually varies with the type of tissue, but an average
velocity for soft tissue is assumed. This equipment is designed
for, and the accuracy statements listed on are based on, an
assumed average velocity of 1540 m/s. The percent accuracy
when stated applies to the measurement obtained (not the full
scale range). Where the accuracy is stated as a percent with a
fixed value, the expected inaccuracy is the greater of the two.
Table 7-2: Measurement accuracy
Measurement Unit Useful range Accuracy Probe
Distance
Axial cm Full screen ±3% or ±1 mm,
whichever is greater Both probes
Lateral cm Full screen ±5% or ±1 mm,
whichever is greater Shallow