Part I Flashcards
-oscillation accompanied by the transfer of energy that travel through a medium or a vacuum
-has cyclic variations
Waves
the back and forth movement at a regular speed
Oscillation
-any sequence of changes in molecular motion
-one compression and one rarefaction
Cycle
transmittal to distant regions remote from the sound source
Propagation
2 Types of Propagation
Compression
Rarefaction
-area of longitudinal wave where particle are spread apart (low pressure)
-occurs after compression, compressed particles intransfer energy
Rarefaction
-area of the longitudinal wave where where particle are close together (high pressure) ex. soundwave
-mechanical deformation
Compression
2 Types of Wave
Longitudinal Wave
Transverse Wave
particle in the medium oscillates in the same direction as the wave energy propagation or PARALLEL with each other
Longitudinal Wave
oscillates PERPENDICULAR to the direction as the wave displacement (perpendicular with velocity of propagation)
Transverse Wave
series of compression and rarefaction, wave front - longitudinal waves
Sound
reflection of incident energy pulse
Echoes
T/F sound waves travel faster in solid than in gas
True
4 Acoustic Variables
Pressure
Density
Temperature
Distance (Particle Motion)
[acoustic variable]
-concentration of force
-force divided by the area in a fluid
-Pascal = 1 N/m²
-atm = 760 mmHg
-kg/ms² or lbs/in²
Pressure
[acoustic variable]
-concentration of medium particles (matter)
-kg/m²
Density
[acoustic variable]
-warming of particle within energy
-C°, F°, K
Temperature
[acoustic variable]
-particle displacement between wave
-m, ft
Distance
normal audible sound (Hz)
20 to 20, 000 Hz
-low frequency sound
-below 20 Hz
Infrasound
-above 20,000 Hz or 20 kHz
-frequency greater than upper limit of the human hearing range
Ultrasound
-utilize 3 to 10 MHz
-uses ultrasound energy and acoustic properties of the body to produce image
Diagnostic Ultrasound
utilize 15 to 20 MHz
Therapeutic Ultrasound
-(a) pulse transmitted through medium, (b) reach tissue (c) create echoes, (d) sound is reflected
-acquire and record echoes arising from tissue interfaces
-construct “acoustic map” of tissues
Pulse Echo
[year; animal]
-naturally occurring animals produces ultrasounds
-has transceivers
1790-Bats
[year; person]
-discovered Piezoelectric Effect
1880-Pierre Curie
‘piezin’ Greek work, means [.. ]
To press
polarization of substances when they are pressed
Piezoelectric Effect
basic fundamental principle of ultrasound
Polarization
[year; person]
-published about high frequency; sound and the possibility of using sound to produce images
Roentgen
-“HEART” of ultrasound
-can transmit and receive sound
Transducer
first transducer used to detect icebergs
Hydrophone
-first active material in transducer
-first piezoelectric material used in transducer
-when hit with electricity, it will produce sound waves
-can produce and receive sound
Quartz
[event]
-developed SONAR (Sound Navigation and Ranging)
-bombard the ocean depths to know the presence of enemies
WWI
[year; used in..]
-transducer used in industry as a testing agent
1940s- frictional heat for sealing thermal plastic package
[year]
-ultrasound used in field of medicine
1950s
[year]
-first ultrasound machine
-big as an iron
1980s
2 Types of Biological Effects
Thermal Effects
Mechanical Effects
-biologic tissues absorb ultrasound energy and convert it to heat
-dependent in rate of heart deposition and heat removal dissipation
Thermal Effects
-dependent/determined on ultrasound intensity and absorption co-efficient of tissues
-ex. bone - high absorption co-efficient
heat deposition
-tissue temperature rises 1-2° (below damaging level)
Diagnostic Ultrasound
can apply damaging levels with high frequency and longer pulse duration
Some Doppler Instruments
-radiation pressure is an effect of [..]
Mechanical Effect
movement of particles in the medium or a torque of the tissue structures in the acoustic streaming
Radiation Pressure
steady circulatory flow
Acoustic Streaming
-sonically generated activity of highly compressible bodies composed of gas and/or vapor
-by high energy deposition over a sort period (short pulses)
Cavitation
2 Types of Cavitation
Stable Cavitation
Transient Cavitation
peak pulse needed to power for transient cavitation to occur
1kW/cm²
High Power Levels/Longer Duration Doppler Studies
[two damages]
Macroscopic Damage
Microscopic Damage
[damage] ex. rupturing of blood vessels, lower duration doppler studies, breaking up of cells
Macroscopic Damage