FujiFilm VisualSonics Vevo F2 User Manual page 237

Transmit Delays on page 259: Controls when each channel within a transmit aperture emits a signal.
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Transmit delays are used to control the manner in which transducer signals reach the target.
Waveforms on page 264: Controls the voltage pattern that is applied to the transducer to generate an
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ultrasound signal.
Pulse Sequences on page 272: Controls the sequence of actions and transmit/receive events
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carried out by the ultrasound system. This includes:
Ordering transmit/receive events.
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Setting up the timing between transmit/receive events.
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Enabling or disabling trigger events.
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Applying any other settings to the system.
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For more information about the VADA configuration panel, refer to Navigation on page 251.
Hardware Limitations
While VADA Mode aims to provide full customizability over the system, certain settings may not be possible
due to hardware limitations. For example, certain elements cannot be set to fire at the same time during
system transmit and receive.
Transducer Thermal Management
In standard imaging modes (B-Mode, PA-Mode), the Vevo F2 has been calibrated with acoustic power and
intensity tests to prevent the surface of the transducer probe from exceeding 50°C while imaging in air
without coupling materials. While some limits have been put in place for pulse sequences in VADA mode, it
cannot be guaranteed that a given pulse sequence will not induce dangerous levels of heating due to a
combination of voltage, pulse repetition interval (PRI), aperture, transmit waveforms and imaging session
length.
To minimize the chance of heating issues, FUJIFILM VisualSonics recommends running all sequences at
the lowest voltage setting that will achieve the desired data output. Perform thermal validation of all
sequences using a thermocouple or some other thermal measurement equipment before using them in
experiments.
Known Causes of Increased Transducer Heating
Although full thermal models are difficult to derive for all VADA pulse sequences, particular combinations of
parameters have been found to be more likely to cause increased heating of the transducer surface.
Be aware that the following characteristics are known to cause transducer heating:
Low PRI (Especially very shallow imaging depths, or disabling the Display Channel Data setting in
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the Preview tab of the VADA Configuration Panel)
Long transmit waveforms
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Large, stationary apertures
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Very long pulse sequences, particularly on the L38xp
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Modes
Vevo F2 Imaging System User Manual
237