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CHAPTER 2 - ULTRASOUND PHYSICS - Coggle Diagram
CHAPTER 2 - ULTRASOUND PHYSICS
Ultrasound
machine that uses high frequency sound waves & their echoes to help to determine the size, shape & depth of abnormality
Waves
repeating disturbance / movement that transfer energy through matter / space
Wavelength & frequency
The higher the frequency the shorter is the wavelength the better the resolving of small structures but lesser the penetration
Wavelength & frequency are inversely related
Amplitude
The amplitude of a wave is directly related to the energy of a wave
Amplitude of transverse wave is distance between crest / a trough & the position of the medium at rest which is the rest position
Sound propagation (Velocity)
Sound travels through different media at different speeds. For example, sound travels faster through water than it does through air
Speed of sound through a material depends on both density & compressibility of the material
Density: denser the material, therefore it have greater inertia, so it velocity decrease
Compressibility: velocity is inversely proportional to liquid & solids propagates sound more rapidly than gases
Power (W)
the rate at which work is done / the rate of flow of energy through a given area
Sound intensity
the energy that the sound wave possesses expressed in power per unit area
Interaction of Ultrasound
Beam with Tissues
Reflection
Attenuation
Refraction
Diffraction
Scatter
Absorption
Ultrasound Production
Transducer contains piezoelectric elements / crystals which produce the ultrasound pulses
Elements convert electrical energy to mechanical ultrasound wave or vice-versa
Piezoelectric Effect
Definition: the principle of converting energy by applying pressure to a crystal
The reverse of piezoelectric effect converts the energy back to its original form called pulse-echo principle
Parameters of Pulsed Sound
Pulse Repetition Frequency (PRF)
Pulse Repetition Period (PRP)
Pulse Duration
Duty Factor
Spatial Pulse Length (SPL)
Components of
Ultrasound machine
Transducer
CPU
Display
Keyboard / cursor
Disc storage device
Printer
Transducer-Parts
Piezoelectric material
Sensor electrodes
Insulated layer
Backing block
Acoustic insulator
Insulating cover
Transducer housing
Couplant
Material that facilitates the transmission of ultrasonic energy from the transducer into the test specimen
Necessary to overcome the acoustic impedance mismatch between air & solids
Coupling agents
Water soluble gel
Water
Disinfectant fluid