GE LOGIQ A100, Техническая публикация

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Probes
268
LOGIQ
t α
100 User Manual
2211157–100 Rev 0
Acoustic Output
Control Parameters which Affect Acoustic Sound
The transmit acoustic power and intensity output of the
imaging system is related to various control settings which
can be changed during the course of an exam. The
operator should be aware of which controls affect output so
as to obtain the optimal image, while at the same time
exposing the patient to only minimum ultrasound energy.
The following parameters can affect acoustic output.
Focus Changing the focus to optimize the image over a
particular region of the scan changes the depth at which
the maximum intensities may occur. Typically, the region
of maximum intensity is close to the focal distance.
Values reported represent the maximum intensity at one
particular focal depth. All other focus depths result in
lower values.
M-Mode Placing the machine into M-Mode affects the acoustic
output of the system. In M-Mode, repetitive pulse firings
occur on the same scan line (corresponding to the M-Mode
vector displayed) which increased the time–average of
SPTA intensity along the scan line chosen.
The SPTA intensity is typically increased by a factor of 30
to 60 times over that in B-Mode. In almost all cases, the
total output power and the pulse average intensities (i.e.,
SPPA or I–m) are not affected, even along the scan line
chosen.
B/M-Mode In this combination mode, both B- and M-Mode vectors
are generated by the machine. The SPTA intensity will
be increased along the M-Mode line selected, but
typically not to the extent as when M–Mode alone is
selected. As with M-Mode, the SPPA, I–m and total
power remain unchanged.
The SPPA and I–m intensities remain relatively constant,
regardless of mode selected. The SPPA intensity is
strongly affected by mode selection, as a result of more
pulses being directed at the specific site selected. The
SPTA intensity is increased in M-Mode over B-Mode.