MODULE 1 Flashcards
Successive oscillation accompanied by a transfer of energy that travels through a medium or vacuum
Waves
A mechanical wave that needs a medium in order to be transmitted
Soundwaves
Reduction in pressure
Low density
Rarefraction
Increase in pressure
High density
Compression
2 types of propagation
Rarefraction
Compression
Transmittal to distant regions
One to another molecules in motion
Propagation
2 types of waves
Mechanical Wave
Electromagnetic Wave
Needs a medium to be transmitted
Mechanical Wave
same direction
parallel with each other
Longitudinal Wave
works on both medium/ vacuum
Electromagnetic Wave
Perpendicular to the direction
Transverse Wave
mechanical energy that propagates through a medium by compression and rarefraction
Sound
Reflection of the incident energy pulse
Echoes
Medium of Sound
solid> liquid> gas
solid bcs it is compacted
Enumerate Acoustic Variables
Pressure
Density
Temperature
Distance
Normal audible sound
Human hearing range
20 to 20,000 Hz
below 20 Hz
Infrasound
above 20,000 Hz (20kHz)
faster than our ability to hear
Ultrasound
Therapeutic Ultrasound
15 to 20 MHz
Diagnostic Ultrasound
3 to 10 MHz
Construct “acoustic map” of tissues
Acquire and record echoes arising from the tissue interfaces
Pulse Echo Technique
1790
Bats
Naturally produces ultrasound
Polarization substances when pressed & basic fundamental principle of UTZ
Piezoelectric Effect
Piezen means
to press
Heart of UTZ
Transducer
1st piezoelectric material used in transducer
Quartz
SONAR
Sound Navigation & Ranging
Used in WW1, to know if there are enemies
1980s
1st UTZ machine
as big as iron
Biologic Effects
Thermal Effects
Mechanical Effects
Tissue absorb ultrasound energy and convert it to heat
Thermal Effects
Thermal effect is dependent on the rate of these..
Heat deposition
Heat dissipation
movement of particles in the medium
define torque on tissue structures
Radiation pressure
known as pulser
provide electrical voltage for exciting the piezoelectric elements
Transmitter
produces and detexts ultrasound
converts electric energy to mechanical sonic energy and vice versa
Transducer/ Probe
Most expensive part of UTS unit
Transducer
Major components of Transducer
Acoustic Lens
Backing Material/ Damping Material
Electrical Connectors
Matching Layer
Physical Housing
Piezoelectric Elements
provides structural support
acts as an electrical and acoustic insulator
Physical Housing
made of thin film of gold or silver
formed in front and back of the crystal
Electrical Connectors
- reduces vibration (ring down time)
- control length of vibration from the front phase
- dampens vibration to create and ultrasound pulse with short spatial pulse length to preserve axial resolution
Backing Material/ Damping Material
range of frequencies
Bandwidth
reduce beam width of transducer
improves lateral/axial resolution
aluminum, perspex, polystyrene
Acoustic Lens
- interface between transducer and tissue/ patient
- minimizes the acoustic impedance differences between the transducer and patient
- improve transmission into the body
Matching Layer
- used to eliminate air pockets that could attenuate and reflect the ultrasound beam
- hypoallergenic
Acoustic Coupling Gel
How piezoelectric material act..
Electricity (AC) is applied to the piezoelectric material which vibrates (thru expansion & contraction) to produce mechanical sound or pressure waves