Chapter 2: System Overview 5
ThePowerSubsystemprovidesthesystempowerandprotectsthehardwarefromdestructiveand/or
unsafeconditionsbydetectingfailuresinthesystemthroughhardwareandsoftwaremonitors.Detection
ofafaultresultsindisablingofthepulsersupply,andsignalingofanerrortotheControlGroup.Thepower
subsystemincl ud es
thebatterypackandbatterychargingelectronics.
Description of Operating Modes
2D Mode 2D mode is a two dimensional image of the amplitude of the echo signal. It is used for
location and measurement of anatomical structures and for spatial orientation during
operation of other modes. In 2D, a two-dimensional cross-section of a 3-dimensional soft
tissue structure such as the heart is displayed in real time. Ultrasound echoes of different
intensities are mapped to different gray scale or color values in the display. The outline of
the 2D cross-section may be a rectangle, parallelogram, trapezoid, sector, or a full circle,
depending on the particular transducer used. 2D mode can be used in combination with
any other modes.
Color
Doppler
(Color)
In color Doppler, a real-time, two-dimensional cross-section of blood flow is displayed. The
2D cross-section may be presented as a rectangle, parallelogram, trapezoid, sector, or a full
circle, depending on the particular transducer used.
The 2D cross-section is presented as a full color display, with various colors being used to
represent the velocity, both positive and negative, of the blood flow echoes. Often, to
provide spatial orientation, the full color blood flow cross-section is overlaid on top of the
gray scale cross-section of soft tissue structure (2D echo). For each pixel in the overlay, the
decision of whether to display VCD, gray scale (echo) information or a blended combination
is based on the relative strength of echoes from the soft-tissue structures and from the red
blood cells.
A high pass filter (wall filter) is used to remove the signals from stationary or slowly moving
structures. Tissue motion is discriminated from blood flow by assuming that blood is
moving faster than the surrounding tissue, although additional parameters may also be
used to enhance the discrimination. The remaining signal after wall filtering may be
averaged over time (persistence) to present a steady state image of blood flow distribution.
Variance information may also be displayed to provide information when large variance is
observed in the velocity information.
Color Power
Doppler
(CPD)
In CPD, a real-time two-dimensional cross-section of blood flow is displayed. The 2D
cross-section may be presented as a rectangle, parallelogram, trapezoid, sector, or a full
circle, depending on the particular transducer used.
The 2D cross-section is presented as a full color display, with various colors being used to
represent the power in blood flow echoes. Often, to provide spatial orientation, the full color
blood flow cross-section is overlaid on top of the gray scale cross-section of soft tissue
structure (2D echo). For each pixel in the overlay, the decision of whether to display CPD,
gray scale (echo) information or a blended combination is based on the relative strength of
echoes from the soft-tissue structures and from the red blood cells.
A high pass filter (wall filter) is used to remove the signals from stationary or slowly moving
structures. Tissue motion is discriminated from blood flow by assuming that blood is
moving faster than the surrounding tissue, although additional parameters may also be
used to enhance the discrimination. The power in the remaining signal after wall filtering
may be averaged over time (persistence) to present a steady state image of blood flow
distribution.
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