Ultrasound Modes

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Ultrasound Modes
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Ultrasound Modes

• A Mode presents reflected ultrasound energy on a
  single line display. The strength of the
  reflected energy at nay particular depth is
  visualized as the amplitude of the waveform.
• B Mode converts A Mode information into a two
  dimensional grayscale display.
• C Mode is a color representation of blood flow
  velocity and direction.
• D Mode is a spectral representation of blood flow
  velocity and direction.
• P Mode is used to visualize very low blood flows
  in color. Unlike C Mode, this mode does not show
  the operator flow direction.
• Triplex is the simultaneous operation of B Mode,
  C Mode and D Mode.
• M Mode is a scrolling display allowing the
  operator to view and record organ motion.

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Axial Resolution

• Another concern is Resolution.
• Axial resolution is corresponds directly to the
  wave length characteristics of the Ultrasound
  wave. As frequency increases wave length shortens
  allowing for greater resolution. What we loose is
  penetration. Again as frequency increases
  penetration decreases. Higher frequencies also
  provide finer tissue grain or smoothness. A less
  grainy look.

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Lateral resolution

• In simple ultrasound systems Lateral resolution
  is attributed to physical focus characteristics
  of the crystal element. The concaved shape of the
  element provides focus to the beam and the width
  of the beam at any particular point effects the
  ability of the ultrasound system to resolve small
  objects that are side by side.

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Transverse resolution

• Transverse resolution is unique to the phase
  array probe. It is the ability of the probe to
  resolve objects side by side, as in lateral
  resolution, but in this case it is measured
  transverse to what would be considered the normal
  imaging plane. Again this is assuming simplest
  probe construction.

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Contrast Resolution

• The ability of the system to resolve adjacent
  bright reflectors is called contrast resolution.
  This is in small part due to the cumulative
  effects of axial and lateral resolution. The
  systems scan converter plays a large role is this
  characteristic.

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Diagnostic Ultrasonography
Displaying Monitor
Transducer / Probe
Keyboard
Probe Connector
Printer (B/W Color)
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TRANSDUCERS

• Device that can change one form of energy into
  another.

Piezoelectric property
Piezoelectric material

• The necessary element for generating acoustic
  waves.

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Piezoelectric effect
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Transducer Design
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Echoes from Two Interfaces
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Echoes from Internal Organ
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DISPLAY TECHNIQUES
A- mode
M- mode
B- mode
Doppler
Pulsed
Continuos
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1) A- mode
Block diagram of an A-scan instrument. A pulser
circuit triggers the transducer, and the
saw-tooth generator. The T/R switch isolates the
receiver amplifier during transmission.
Amplitudes of the received echo signals are
presented on the vertical axis of the CRT.
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2) B-mode
Brightness modulation
CRT
Vert.
Time variable gain
Amp
Horiz.
Pulser circuit
Beam steering control unit
T/R switch
Saw tooth voltage sweep
A pulser circuit triggers the transducer, and the
saw tooth generator. The T/R switch isolates the
receiver amplifier during transmission. For each
scanning line, the amplitudes of the received
echo signals are modulated to brightness.
Steering unit is controlling the synchronization
process.
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3) M- mode
Slow voltage ramp
CRT
B
Vert.
Time variable gain
Amp
Horiz.
Pulser circuit
Sawtooth voltage sweep
Trigger
T/R switch
Body
B
A
Fixed organ
Transducer
Moving Organ
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TRANSDUCER MODES
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TRANSDUCERS TYPES
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TRANSDUCERS TYPES
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Linear Probe Image
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Sector (Phased array) Probe
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Convex Probe Image
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Real Time 3D
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Fetal Spine
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Reconstructional 3-D
Obstetrics
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Ultrasound Machines
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Ultrasound Machines

• Function
• Diagnostic ultrasound machines are used to give
  images of structures within the body. This
  chapter does not deal with other kinds of machine
  (e.g. therapeutic and lithotripsy). The
  diagnostic machine probes, which produce the
  ultrasound, come in a variety of sizes and
  styles, each type being produced for a particular
  special use. Some require a large trolley for all
  the parts of the unit, while the smallest come in
  a small box with only a audio loudspeaker as
  output. They may be found in cardiology,
  maternity, outpatients and radiology departments
  and will often have a printer attached for
  recording images. Unlike X-rays, ultrasound poses
  no danger to the human body.
• How it works
• The ultrasound probe contains a crystal that
  sends out bursts of high frequency vibrations
  that pass through gel and on through the body.
  Soft tissue and bone reflect echoes back to the
  probe, while pockets of liquid pass the
  ultrasound straight through. The echoes are
  picked up and arranged into an image displayed on
  a screen. The machine offers a number of
  processing options for the signal and image and
  also allows the user to measure physical features
  displayed on the screen. This requires the
  machine to incorporate a computer.

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How TO CHOOSE TRANSDUCER
1) FREQUENCY
2) SCANNING ANGLE
3) RADIUS or LENGTH
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WHAT WE HAVE TO KNOW BEFORE PURCHASING A G.P.U.S
WHAT TYPES OF EXAMINATION ARE TO BE CARRIED OUT ?
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1. TRANSDUCER Curvilinear or combination of
linear and sector.
2. FREQUENCY Standard transducer should have
central frequency of 3.5 MHz.
3. ANGLE for Sector probe should be 40 or more,
linear array should be 5 - 8 cm
long.
4. FRAM RATE 15 - 30 Hz for linear array,
5 - 10 Hz for sector array.
5. FRAM FREEZE DENSITY at least 5125124 bits
to provide 16 gray levels
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6. ELECTRONIC CALIPERS one pair at least, with
Quantitative readout.
7. ADD DATA IS POSSIBLE patient identification,
hospital name, date of examination etc.
8. HARD COPY should be possible.
9. MONITOR at least 13 cm 10 cm (preferably
larger)
10. STABILIZING should be able to stabilize
voltage variation of /- 10.
11. Biometric tables (it may not be universal
and should be adjusted for local standards.
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WHAT WE HAVE TO CHECK WHEN WE RECEIVE THE SCANER
SERVICE MANUAL
USERS MANUAL
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Checking every instruction in the manual may
takes time. But if you do so, you will save time,
money, and frustration.
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CHECK LIST
1. Voltage setting should be compatible with the
electrical supply.
2. Interference on the screen/ whit sparks.
3. Transducer and cables test.
4. Check the cursor / measuring length,
5. Check the accessibility of the biometrics or
measurement tables.
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IMAGE ARTIFACTS
Any missing or distorted image that does not
match the real image of the part being examined
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ARTIFACT'S CAUSES

• Acoustic characteristics of the tissues.
• Scanners settings.
• Lack of users experience.
• Defected part within the scanner.

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To confirm any suspected abnormality, Use
multiple projections at different angles

• COMMON ARTIFACTS

• Cysts artifact (strong back-wall effect).
• Abdominal wall artifact.
• Gas artifact.
• Reverberation artifact.
• Incomplete imaging artifact.
• Gain artifact.
• Shadows artifact.

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DAILY CHECKS "visual"

• Visually inspects all transducers.
• Cable, cracked surface, punctured,
  discolored casing

• Visually inspect the power cords.

• Verify that the trackball and DGC controls
  appears clean and free from gel or other
  contaminants.

Once the system is powered on
Verify that the monitor displays CORRECTLY the
connected transducers identification, current
date, time.
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DAILY ADJUSTMENT

• FOCUS.
• DEPTH GAIN COMPENSATION.
• OVERALL GAIN.
• ZOOM.
• MONITOR (B/C).

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CLEANING AND DISINFECTING