Acoustic Measurement Uncertainty
Measurement
Uncertainty (Percentage,
95% Confidence Value)Quantity
Pr: ±11.3%Pr is the underated peak rarefactional
pressure measured in megapascals (MPa).
±10%Wo is the ultrasonic power in milliwatts
(mW).
±4.7%f
c
is the center frequency in megahertz
(MHz) (NEMA UD-2 definition).
PII.3: +18% to -23%PII.3 is the derated spatial-peak pulse
intensity integral in joules per square
centimeter (J/cm
2
).
Operator Safety
The following issues and situations can affect operator safety when you are using
an ultrasound system.
Repetitive Strain Injury
Repetitive ultrasound scanning has been associated with carpal tunnel syndrome
(CTS) and related musculoskeletal problems. Some investigators have looked at
a large population of sonographers with different types of equipment. An article,
with feedback from a smaller geographical area, makes the following
recommendations:
• Maintain your joints in optimum positions with a balanced posture while
scanning.
• Allow frequent breaks to give soft tissue a chance to recuperate from
awkward positions and repetitive movement.
• Avoid gripping the transducer with excessive force.
iE33 User Manual
64
4535 616 23901
Safety
2
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