2. CONTENTS
INTRODUCTION
PRINCIPLE OF ULTRASOUND
GENERATION AND DETECTION OF ULTRASOUD
MAIN IMAGING MODES
ULTRASOUND MACHINE
TRANSDUCER PROBES
WORKING PROCEDURE OF ULTRASOUND
APPLICATIONS
BENEFITS
LIMITATIONS
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3. ULTRASOUND: BASIC DEFINITION
Ultrasound is acoustic(sound) energy in the form of waves
having a frequency above the human hearing range(i.e.
20KHz)
Ultrasound is a way of using sound waves to look inside the
human body.
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4. ULTRASOUND IS A LONGITUDINAL MECHANICAL WAVE WHERE
PARTICLE DISPLACEMENT IS PARALLEL TO THE PROPAGATION OF
WAVE
Longitudinal
wave
Transverse
wave
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5. PRINCIPLE OF ULTRASOUND
Ultrasound waves are created by a vibrating crystal within a
ceramic probe.
Waves travel through the tissue and are partly reflected at each
tissue interface.
“Piezoelectric “ principle- electric current causes crystal to
vibrate, returning waves create electric current.
Following phenomenon occur when ultrasound propagates
through medium:
Reflection
Refraction
Diffraction
Attenuation
Scattering
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6. GENERATION OF ULTRASOUND
Ultrasound waves are usually both
generated and detected by a piezoelectric
crystal.
The crystal deforms under the
influence of an electric field and, vice-
versa.
When an alternating voltage is applied
over the crystal, a compression wave
with the same frequency is generated.
Generally used piezoelectric
materials are: PZT(lead zirconate titanate)
and PVDF( polyvinylidene difluoride)
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8. PIEZOELECTRIC CRYSTALS
The thickness of the crystal determines the frequency
of the scan head.
Low
Frequency 3
MHz
High
Frequency
10 MHz
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10. ULTRASONOGRAPHY
Ultrasonography or diagnostic sonography is an
ultrasound based diagnostic imaging technique used
for visualizing internal body structures.
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11. MAIN IMAGING MODES
GREY SCALE
IMAGING
A-Mode
B-Mode
M-Mode
DOPPLER IMAGING
Continuous wave
Doppler
Power Doppler
Color Doppler
Duplex Doppler
Pulsed wave
Doppler
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12. AMODE
Simplest form of ultrasound
imaging which is based on
the pulse-echo principle.
A scans can be used to
measure distances.
A scans only give one
dimensional information
Not so useful for imaging
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13. B MODE
B stands for Brightness
B scans give two dimensional
information about the cross-
section.
Generally used to measure
cardiac chambers dimensions,
assess valvular structure and
function.
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14. M MODE
M stands for motion
This represents
movements of
structures over time.
M Mode is commonly
used for measuring
chamber dimensions.
This is analogous to
recording a video in
ultrasound.
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15. DOPPLER IMAGING
It is a general term used to
visualize velocities of moving
tissues.
Doppler ultrasound evaluates
blood velocity as it flows
through a blood vessel.
Blood flow through the heart
and large vessels has certain
characteristics that can be
measured using Doppler
instruments.
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16. DOPPLER EFFECT
Apparent change in received frequency due to a relative
motion between a sound source and sound receiver
Sound TOWARD receiver = frequency
Sound AWAYfrom receiver = frequency
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17. WHAT DEFINES A GOOD
DOPPLER
No background noise
Clear audible signal
Accurate display of velocities
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19. APPLICATIONS
Applications available on the ultrasound system
Abdominal
Cardiac
Gynecological
Intraoperative
Musculoskeletal
Neonatal head
Obstetrical
Pediatric
Transcranial and Trans esophageal
Vascular
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21. TRANSDUCER
Electronic device that converts energy from
one form to another.
Ultrasound transducers converts electrical
pulse into sound pulse and sends sound pulse
into the body and listens for returning echoes
generated by tissue interfaces and again
converts sound pulse into electrical signal.
Piezoelectric transducers are used in
ultrasound.
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23. TRANSDUCER PROBES
Probes are generally described by the size and shape of
their face(“footprint”). There are 3 basic types of probe
used in emergency and critical-care ultrasound.
Linear array probe
Curvilinear array probe
Phased array probe
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24. STRAIGHT LINEARARRAY
PROBE
It is designed for superficial imaging
Crystals are aligned in a linear fashion within a flat head and
produce sound waves in a straight line.
Image produced is rectangular in shape
Probe has higher frequency ( 5-13 MHz) providing
better resolution and less penetration.
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25. CURVILINEAR PROBE
Also called convex probe
Used for scanning deeperstructures
Crystals are aligned along a curved surface which results in a wide field of view
Image created is sector shaped.
Probes have frequency between 1-8 MHz allowing greater penetrationand
less resolution.
Generally used in abdominal and pelvic applications.
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26. PHASEDARRAY PROBE
Crystals are grouped closely together.
Sound waves originate from a single point and fan outward,
creating a sector-type image.
Has smaller and flatter footprint than the curvilinear probe.
Probe has frequency between 2-8 MHz
Generally used for cardiac imaging, Imaging between ribs and
small spaces.
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27. ENDOCA
VITARY PROBE
Has a curved face
Has higher frequency than curvilinear probe ( 8-13
MHz)
Probe’s elongated shape allows it to be inserted
close to the anatomy being evaluated.
Curved face creates a wide field of view of almost
1800
High frequency provides superior resolution
Most commonly used for gynecological applications
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29. APPLICATIONS
Obstetrics and Gynecology
1. Measuring the size of the fetus
2. Monitoring the baby for various procedures
Cardiology
1. Seeing the inside of the heart to identify abnormal functions
2. Measuring blood flow through the heart and major blood
vessels
Urology
1. Measuring blood flow through the kidney
2. Locating kidney stones
3. Detecting prostate cancer at early stage
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30. BENEFITS
Images muscle, soft tissues very well
Renders “live images” where most desirable section is selected
Shows structure of organs
No long-term side-effects
Widely available and comparatively flexible
Highly portable
Relatively inexpensive
Spatial resolution is better in high frequency ultrasound
scanners
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31. LIMITATIONS
Sonographic devices have trouble penetrating bone
Sonography performs very poorly when there is a gas
between the transducer and organ of interest
Body habitus has large influence on image quality
Method is operator-dependent
No scout image as there is with CT and MRI
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