Controls Affecting Acoustic Output - GE Vscan Air Manual

Controls Affecting Acoustic Output

Input Parameters
Transmit frequency
Transmit apodization
Focal depth
Steering angle
Sector size
Pulse repetition frequency
Pulse length
Mode combination
Application
Acoustic ouput control
Probe sensitivity
–
Vscan Air User Manual
Direction GP092020-1EN Rev 18
The initial means by which the user can affect acoustic output
are by 1) selecting a probe, 2) selecting an application (exam
category) and then 3) selecting the imaging mode or imaging
characteristics (depth, color ROI center position). This is
achieved through an acoustic output control scheme in which all
parameters that directly or indirectly affect acoustic output are
fed to the control algorithm. The algorithm estimates all relevant
parameters and compares them to the FDA limits.
Output levels remain below the limits with a 95% confidence
margin. The absolute maximum allowable output for all
applications is:
• ISPTA less than or equal to 720 mW/cm2
• MI less than or equal to 1.9
• TI less than or equal to 6
The Acoustic Output Control Scheme
Control Algorithm
---->
---->
---->
----> Output control never to
exceed limit minus
---->
tolerances
---->
---->
----> I
SPTA
----> TIS/TIB/TIC
----> MI
---->
FDA Limits @ 95%
confidence tolerance
Acoustic Output
Output Parameters
----> Transmit voltage control to
Beamformer
----> Thermal/mechanical
Indices to Output Display
8-5