Ultrasound and phosphophoresis Flashcards
definition: mechanical pressure waves that requires a medium and travels by deformation or vibration
sound waves
definition: water soluble gel
medium
(true/false) Sound waves at lower frequencies diverge in all directions
true
definition: When a crystal generates an electric voltage when mechanically compressed
piezoelectricity
definition: When a current is applied to a crystal generates and oscillatory deformation of the crystal
reverse piezoelectric effect
definition: the distance between the two peaks in a pressure wave
wavelength
The head of an ultrasound is a transducer that converts ___ energy into ___ energy.
electrical, sound
definition: the # of cycles per second
frequency
definition: the flow of energy in an uninterrupted wave (100% duty)
continuous
definition: the flow of energy with periodic interruptions
pulsed
What frequency due to use to target a structure >2 cm below the surface of the skin?
1 MHz
What frequency do you use if you are targeting a structure 1-2 cm from the surface of the skin?
3 MHz
definition: the acoustic power of the ultrasound beam at its highest point that usually occurs within the central 1/3 of the ERA
spatial peak
definition: a measure of the avg. acoustic power across the ERA (intensity)
spatial average intensity
definition: The surface area of the ultrasound head that is in contact with the skin
effective radiating area (ERA)
The ultrasound treatment area should be ___ times the size of the ultrasound head
2x
When using an ultrasound, move in circles that are about ___ second each.
1
spacial peak intensity : spatial avg. intensity
beam non-uniformity ratio (BNR)
What is an acceptable BNR for an ultrasound machine?
6:1
The (smaller/larger) the BNR, the more uniform the ultrasound beam will be.
smaller
Duty cycle= _____ / _____
on time/off time
definition: the material’s ability to transmit sound and is related to molecular density and the material’s structure
acoustical impedance
(low/high) impedance is when the transmission of the Ultrasound beam is high and the material absorbs little energy/sound
low
(low/high) impedance is when the ultrasound transmission is low and the material absorbs more of the energy
high
definition: when the sound wave is bent as opposed to bounce back
refraction
definition: when a reflected wave travels back its original path, it can interact with additional sound waves that are coming after it. This can cause an increased intensity
standing wave
Standing waves can cause ____.
burns and tissue damage.
definition: movements within the cell that alter the cell membrane permeability and cellular activity
microstreaming
definition: gas bubbles that compress and expand during ultrasound exposure that contribute to cell membrane changes
cavitation
definition: the violent collapse of gas bubbles
unstable cavitation
What are the thermal and mechanical effects of ultrasound?
microstreaming, cavitation, unstable cavitation
What are contraindications for using ultrasound as a modality?
- cardiac pacemakers
- pregnancy
- moving over epiphyseal plates on children
- cancer
- infection
What are some precautions taken into consideration when using an ultrasound?
- sensory/circulation deficits
- communication issues/barriers
- metal/plastic implants
Bone heats up (slower/faster) than muscle and fat.
faster (DO NOT GO OVER BONE)
(true/false) you want to use thermal effects in a patient with delayed tissue healing and prolonged inflammation
false (this will actually cause more inflammation)
You should use an intensity of ___ W/cm when going over superficial tissues with an ultrasound
0.5
definition: a type of modality that is used for irregular surfaces such as ankles and wrists
underwater ultrasound
When using an underwater ultrasound, keep the ultrasound head about __-__ cm away from the body part
0.5-3
definition: the use of ultrasound waves to deliver medications transdermally
phonophoresis
