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Display Modes. Display Mode. A mode M mode B mode. A mode. First form of echo display. Echoes displayed as vertical deflection. Horizontal axis represents distance or depth. The vertical axis represents the amplitude of the echoes. A mode. The horizontal position of the A-mode on the

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Display mode
Display Mode

  • A mode

  • M mode

  • B mode


A mode
A mode

  • First form of echo display.

  • Echoes displayed as vertical deflection.

  • Horizontal axis represents distance or depth.

  • The vertical axis represents the amplitude of the echoes.


A mode1
A mode

The horizontal position of the A-mode on the

CRT display depends on the transducer-

reflector time relationship.

  • The electronic beam is swept horizontally by the horizontal sweep generator at a speed of 1540 m/s from left to right.

  • The CRT electron beam is synchronized to start the sweeping action with the application of the transmit pulse voltage.


A mode2
A-mode

The vertical position of the trace is determined

by the voltage signal amplitude from the video

amplifier.

The height of the vertical deflection depends on

the amplitude of the echoes and receiver

function such as the gain and TGC settings.


A mode3
A-mode

Amplitude (y-axes)

Distance (x-axis)


B mode
B-mode

B-mode means Brightness mode.

  • Echoes are displayed brightened dots.

  • The strength of the echoes determines the brightness.

  • The position of the B-mode dot on the screen represents the reflector distance and is determine by the transducer-reflector time relationship.


M mode
M-MODE

  • B mode echoes form an interface that changes position will be seen as echoes moving towards and away from the transducer.

  • If a trace line is place on this interface and the resulting trace is made to drift across the face of a CRT screen a motion pattern is obtained.


M mode1
M-MODE

  • The resulting display shows motion of a reflector over distance and time – a distance time graph.

  • The change in distance (dy) over a period of time dt is represented by the slope of the reflector line of motion.

  • dy/dt = slope = velocity


M mode2
M-MODE

  • If this motion pattern is obtained on moving cardiac structures then the resulting images constitute M-mode echocardiography.

  • M-mode echocardiography is use to evaluate the morphology, movement and velocity of cardiac valves and walls.


M mode tracing
M-mode Tracing

Distance

Time


M mode evaluation
M-mode Evaluation

  • Amplitude

  • Velocity

  • Morphology


Amplitude measurement
Amplitude Measurement

Y2

Amplitude = Y2 –Y1

Y1


Slope measurement
Slope Measurement

Y2

dy = Y2 –Y1

Y1

Slope = dy/dt

T1

T2

dt = T2 – T1


Real time scanner
Real Time Scanner

RT describe an ultrasound system that

  • Acquires

  • Processes

  • Displays

    Images without storing the echo data.



Frame rate
Frame Rate

  • Each sweep of the ultrasound beam produces a frame.

  • The frame is made up of scan lines

  • Each can line is produce by a ultrasound pulse

  • The frame rate depends on the rate of pulse production (pulse repetition frequency) and the number of scan lines in that frame.


Frame rate1
Frame Rate

Frame

Scan lines

Frame rate = PRF/lines per frame


Frame rate2
Frame Rate

Increase Frame Rate by

Increasing PRF

  • Decreasing image depth

    Decreasing # of lines per frame

  • Decrease frame width

  • Decrease Scan line density

    -


Frame rate3
Frame Rate

Frame

Scan lines

Frame rate = PRF/lines per frame


Increasing frame rate decreasing image depth
Increasing Frame RateDecreasing Image Depth

Frame

Scan lines

Frame rate = PRF/lines per frame


Increasing frame rate decreasing scan line density
Increasing Frame RateDecreasing Scan Line Density

Frame

Scan lines

Frame rate = PRF/lines per frame


Increasing frame rate decreasing frame width
Increasing Frame RateDecreasing Frame Width

Frame

Scan lines

Frame rate = PRF/lines per frame


Frame rate4
Frame Rate

Decrease Frame Rate by

Decreasing PRF

  • Increasing image depth

    Increasing # of lines per frame

  • Increase frame width

  • Increase Scan line density

  • Increase # of pulses per scan line

    - Multiple focal zones

    - Color Doppler


Frame rate5
Frame Rate

Frame

Scan lines

Frame rate = PRF/lines per frame


Decreasing frame rate increase image depth
Decreasing Frame RateIncrease Image Depth

Frame

Scan lines

Frame rate = PRF/lines per frame


Decreasing frame rate increasing scan line density
Decreasing Frame RateIncreasing Scan Line Density

Frame

Scan lines

Frame rate = PRF/lines per frame


Decrease frame rate multiple focal zones
Decrease Frame RateMultiple Focal Zones

Frame

Focal Zones

Frame rate = PRF/lines per frame


Decrease frame rate color doppler
Decrease Frame RateColor Doppler

Frame

Scan lines

Frame rate = PRF/lines per frame


Frame rate6
Frame Rate

The faster the moving reflector the

higher the frame required in order to

display continuous motion


Frame rate7
Frame Rate

  • Frame rate – 15 and 60 f/s

  • Can be adjusted by the operator

  • Automatically adjusted as a function of depth and or field of view.


Temporal resolution
Temporal Resolution

Temporal resolution is a measure of the ability to

separate events in time.

The frame rate determines the ability to capture

motion accurately.

The higher the frame rate the better the temporal

resolution.


Temporal resolution1
Temporal Resolution

The following factors affect the frame rate and

thus the temporal resolution.

  • Image depth

  • Wide field of view

  • Multiple transmit focal zones

  • Color Doppler

  • Scan line density


Beam steering
Beam Steering

RT scanners sound beam is steered

rapidly and repeatedly.


Beam steering1
Beam Steering

Steering Mechanism

Mechanical

Electronic

Linear Switched

Linear Phase

Oscillating

Mirror

Rotating



Rotating transducer
Rotating Transducer

Flexible Cable

Rotation Point

Crystal

Membrane


Oscillating transducer1
Oscillating Transducer

Oscillating membrane

Annular array

Coupling membrane


Array transducer
Array Transducer

Linear array

Phased array

Annular array


Beam steering linear phase
Beam SteeringLinear Phase


Beam steering linear phase1
Beam SteeringLinear Phase


Beam steering linear phase2
Beam SteeringLinear Phase


Beam steering linear switched
Beam SteeringLinear Switched


Beam steering linear switched1
Beam SteeringLinear Switched


Beam steering linear switched2
Beam SteeringLinear Switched


Beam steering linear switched3
Beam SteeringLinear Switched






Annular array
Annular Array

Elevational Resolution

Lateral Resolution


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