lesson 3 Flashcards
The application of ultrasound in medicine began in
1950s
is based on
distinguishing the tissues with different
absorbance of ultrasound.
Transmission technology
registers the
pulse is reflected from the boundary of two
tissues with different acoustic resistance.
Reflection Technology (Echo)
- It is a mathematical
formula that describes the behavior of waves in
different mediums - The equation is based on the principles of wave
mechanics, which states that waves can be described by their amplitude, wavelength, and
frequency.
WAVE EQUATION
General ultrasound
waves, the direction of
propagation which coincides with the direction of displacement and velocities of the particles of the medium
Longitudinal Ultrasonic Waves
- waves propagating in a direction perpendicular to the plane in which the directions of displacements
and velocities of body particles lie. - Shear Waves Elastography— measure the stiffness of tissue
Transverse Ultrasonic Waves
- have an elliptical(oval) motion of particles and
propagate over the surface of the material. - Their speed is approx 90% of the shear wave propagation speed, and their penetration deep into the material is equal to approximately one
wavelength
Surface (Rayleigh) Ultrasonic Waves
Is the time-average energy carried by a sound wave through a unit area perpendicular to the
direction of wave propagation, per unit time.
SOUND INTENSITY
- the energy transmitted by a sound wave through the considered surface per unit of time.
- the average value of the ultrasound power per unit area, average specific sound
power, or sound intensity
SOUND POWER
by inhomogeneities of the medium, as a result of which the energy flux in the initial direction of
propagation decreases
Scattering of ultrasound
irreversible transfer of the energy of a sound wave into
other forms (heat)
Absorption of ultrasound
devices used to excite ultrasonic vibrations
and waves in gaseous, liquid, and solid media. It converts energy of some other kind to the energy of the sound field
ULTRASOUND EMITTERS
‘piezo’ suffix of piezoelectric was formed from the Ancient Greek word πιεζω (piezo) meaning
“to press
is the process of using crystals to convert
mechanical energy into electrical energy or vice versa.
Piezoelectricity
what are quartz, silicon dioxide, lead zirconate and
lead titanate
PIEZOELECTRIC CRYSTALS
Converts kinetic or mechanical energy, due to
crystal deformation, into electrical energy. This
is how ultrasound transducers receive the
sound waves
PIEZOELECTRIC EFFECT
produces an electrical charge
when a mechanical vibration or shock is
applied to the material.
Direct Effect
creates a mechanical vibration or shock when
electricity is applied
Reverse Effect
The ability to create an ultrasound echo. Ability
of a tissue to reflect sound waves
ECHOGENICITY
Being echo-free or without echoes (fluid-filled cyst, ascites)
ANECHOIC
Producing echoes of higher amplitude than normal for the surrounding medium
HYPERECHOIC/ ECHOGENIC
areas which have similar echogenicity to each
other
ISOECHOIC
Producing echoes of lower amplitude than the
surrounding medium
HYPOECHOIC
Allowing passage of ultrasound waves without
echoes
SONOLUCENT
