4. AUDIBLE SOUND
• Sound is a form of energy which causes
vibration of molecules within a medium.
• In order to be transmitted, sound requires a
medium containing molecules, and therefore
cannot through a vacuum.
• The production of sound requires a vibration
object.
5.
6. 2 Types of UTZ Waves:
• Longitudinal or Compression
Waves
2. Transverse Waves or Shear
Waves
11. The phase of wave when the
molecules are pushed together is
called compression , and when apart
is rarefaction.
12. Ultrasound
• Ultrasound is the name given to high
frequency sound waves, which are
above the human hearing range.
• Acoustic vibration of frequencies higher
than 20 kHz, non audible by human ear.
• Non-ionizing radiation.
18. Velocity
Velocity= Frequency x Wavelength
The propagation
velocity is the velocity
at which sound
travels through a
particular medium
and is dependent on
the compressibility
and density of the
medium. Usually, the
harder the tissue, the
faster the
propagation velocity
20. 1916 - The first working version of marine
SONAR (Sound Navigation and Ranging)
system was used during the First World War
to detect enemy submarine.
21. Early 1950's - Because air does not
transmitted ultrasound waves, the air
interface between the transducer and
the patient's skin was initially a problem.
Early scanning technique required the
patient to immersed in a bath of water
in order to provide good transmission of
sound wave into the body.
22. Late 1950's - the first contact
compound B-Scanner (using olive oil
as a lubricant) was developed. This
equipment used an articulating arm
to produce static images.
• Water
• Saline
• Baby Oil
23. 1970's - gray scale imaging was
introduced, enabling the display of
a wide range of echo amplitudes.
24. Mid 1970's - real-time scanning
systems were introduced.
Dynamic Sonograhic Information
was available for the first time.
1980's - Doppler Technique is used.
26. Ultrasound exams can help diagnose a variety
if conditions and assess organ damage
following an illness.
Doctors used Ultrasound to evaluate:
• Pain
• Swelling
• Infection
27. Ultrasound is a useful way of examining many of the
body's internal organs, including but not limited to the:
• Heart and blood vessels, including the abdominal aorta
and its major branches
• Liver
• Gallbladder
• Spleen
• Pancreas
• Kidneys
• Bladder
• Uterus, Ovaries, and Unborn Child in Pregnant Patients
• Thyroid
• Scrotum
• Brain in Infants
28. Ultrasound is also used to:
• Guide procedures such as needle biopsies, in
which needles remove cells from an
abnormal area for laboratory testing.
• Image the breasts and guide biopsy of
breast cancer.
• Diagnose a variety of heart conditions,
including valve problems and congestive
heart failure, and to assess damage after a
heart attack. Ultrasound of the heart is
commonly called an "echocardiogram" or
"echo" for short.
29. Doppler Ultrasound helps the Doctor to see and
evaluate:
• Blockages to blood flow (such as clots)
• Narrowing of vessels
• Tumors and Congenital Vascular
Malformations
• Reduced or absent blood flow to various
organs, such as the testes or ovary
• Increased blood flow, which may be a sign of
infection.
31. PIEZOELECTRIC EFFECT
• Piezo - is a Greek word "PIEZEN" that means to
"press or pressure" , therefore piezoelectric
describes the manner in which some
substances become electrically polarized when
stressed.
• This is the ability of a material to generate an
electrical charge in response to applied
pressure.
32.
33. • When a piece of
piezoelectric materials is
compressed a potential
difference is generated
across opposite faces- the
one side becomes positive,
the other becomes
negative.
35. Piezoelectric Materials
Natural
• Quartz
• Tourmaline
• Rochelle Salt
Synthetic
• Lead Zirconate Titanate
• Barium Titanate
• Lead Metaniobate
• Ammonium Dihydrogen
Phosphate
• Lithium Sulfate
36. • Piezoelectric Materials are
cystalline materials composed
of dipolar molecules, which are
positive one end and negative
at the other.
• Normally these dipolar
molecules have a random
arrangement within the
material and they are unable to
align themselves with an
applied electric field.
37. • However, if the
materials are heated
above the Curie
Temperature in
presence of an electric
field, the molecules align
themselves with that
field.
38. • Piezoelectricity was discovered in 1880
by two brothers and French Scientists,
Jacques and Pierre Curie.
39. The Piezoelectric Crystal as
Transmitter of Sound
Piezoelectric materials are used in the
production of ultrasound by converting :
Electrical Energy into Mechanical Energy
(Sound)
40. The Piezoelectric Crystal as
Receiver of Sound
Piezoelectric materials are used in the
detection of ultrasound by converting :
Mechanical Energy (Sound) into Electrical
Energy
41. Note:
• As the crystal diameter decreases,
the beam divergence increases.
• As the crystal diameter increases, the
beam divergence decreases.
