ultrasound

ultrasound

delivery of high frequency inaudible mechanical energy to tissues via transducers

frequency

how often in a sec a mechanical vibration is delivered to tissues via transducer

piezoelectric material

a transducer in US involves an alternate current being applied to a _____ which causes it to expand at a frequency for a mechanical vibrationq

true

using ultrasound can help w making a mechanical vibration in tissue to help heat deep tissue

t or f

false

using ultrasound can help w making a mechanical vibration in tissue to help heat superficial tissue

t or f

coupling medium

US requires a _____ to transmit energy from the head to the tissue

increased

dense tissues like skin fascia and scar tissues tend to absorb _____energy from US

decreased

less dense tissues like adipose tissue and blood tend to absorb ___ energy from US

acoustic impedence

tissues w greater potential to heat will have a higher ___

true

ultrasound leads to cellular changes such as oscillation, deformation, rotation of cells and expansion/contraction of gas bubbles

t or f

false

ultrasound leads to cellular changes such as vibration, deformation, rotation of cells and expansion/contraction of gas bubbles

t or f

acoustic streaming

sound energy causes ____ where there is movement of fluid around cells from the compresion phase of US deforming molecules and cell membranes

cavitation

occurs in respone to US mechanical energy where gas bubbles in tissues expand and contract causing cells to rotate

stable cavitation

occurs when US leads to microstreaming around gas bubbles leads to mech forces on surrounding cells and rotation and twisting

unstable cavitation

occurs when US leads to increased expansion of gas bubbles causing implosion and release of free radicals, pressure and pain

3 MHz

an US frequency of -___ leads to energy being the most absorbed at a depth of 1-2 cm (superficial)

1 MHz

an US freq of ____ leads to energy being the most absorbed at a depth of 3-5 cm (deep)

true

a freq of 3 MHz should be used to treat tissues up to 1.5cm deep and 1 MHz for deeper than 1.5 cm

t or f

false

a freq of 1 MHz should be used to treat tissues up to 1.5cm deep and 3 MHz for deeper than 1.5 cm

t or f

incident

waves of an US head and are delivered are the ____ wave

transmitted

US waves when using a coupling medium are ____ through the tissue

reflected

US waves when exposed to air is ____ to the head

refracted

occurs when the US head is not perpendicular to the tissue leading to the energy become ____

true

when the US head is not perpendicular to the tissue then there will be less energy transmited to the tissue

t or f

false

when the US head is not perpendicular to the tissue then there will be more energy transmited to the tissue

t or f

standing waves

if the US is stationary then the incident and reflected waves coincide leading to _____ which can overheat tissue and pain

true

cooler tissues are more dense than warm leading to a dec in penetration of US energy which is not useful for deep tissues

t or f

false

cooler tissues are more dense than warm leading to a inc in penetration of US energy which is useful for deep tissues

t or f

effective radiating area

the beam area which is the area the transducer covers is also known as the ____

true

when using US the intensity is delivered in w/cm2

t or f

false

when using US the intensity is delivered in watts

t or f

temporal distribution of energy

the intensity of an ultrasound as a function of time is known as the _____

continuous

US when delivered _____ helps w heating tissue and inc in collagen extensibility

pulsed

US when delivered _____ helps with tissue healing, wound healing and helps the delivery of drugs across tissue (phonophoresis)

20% duty cycle

in pulsed when the US is on:off ratio is 1:4 the intensity is 

10% duty cycle

in pulsed when the US is on:off ratio is 1:9 the intensity is

true

duty cycle of 20% is the most common used pulsed intensity

t or f

false

duty cycle of 50% is the most common used pulsed intensity

t or f

temporal peak

the max intensity delivered by the US wave when it is on 

temporal average

the average US intensity calculated over the time when the pulses are delivered or the fxn of temporal peak and duty cycle

true

when US intensity is continuous when the temporal average is equal to the peak

t or f

true

temporal average is the average power over the pulse repetition (on and off time)

t or f

false

temporal peak is the average power over the pulse repetition (on and off time)

t or f

true

US machines will always show temporal peak

t or f

false

US machines will always show temporal average

t or f

spatial peak intensity

the max intensity delivered by the US unit over the beam (middle of head)

spatial average intesity

the average intensity of the entire transducer

beam non uniformity ratio

the ratio of the spatial peak intensity to the spatial average intensity

true

US machines will display the spatial average, and temporal peak intensity

t or f

false

US machines will display the spatial peak, and temporal average intensity

t or f

spatial average temporal peak

the _____ is used to record treatment in patient chart when using US

frequency

rate of expansion and contraction of piezoelectric material (in Hz)

intensity

the amplitude of US energy expressed in W/cm2 w a max of 2 W/cm2 in practice

thermal

US can be ____ which has heating and cellular effects when delivered continuously 

athermal

US can be ____ which has cellular properties when delivered pulsed 

true

absorbed energy in tissue converts to heat which absorption inc w inc tissue density and frequency

t or f

conduction and convection

heat gain in thermal US is modified by ______