Ultrasound Flashcards
what type of healing modality is ultrasound
deep heating
what is the most common deep heating modality
ultrasound
what is the most common heating modality
moist hot packs
2nd most common heating modality
ultrasound
what does the electrical current pass through
crystal 2-3 mm thick
Duty cycle of 100% means what
continuous
results in tissue heating
What is the reverse piezoelectric effect
mechanical deformation of crystal causes an electrical current to form
What is near field
treatment area-fresnel zone
what is far field
fraunhofer zone
what is spatial peak intensity
Isp
peak intensity
watts per cm2
what is spatial average intensity
Isp * duty cycle
ERA (effective radiating area)
area of the sound head that produces sound energy
BNR (beam nonuniformity ratio)
ultrasound beams not uniform across US head
amount of variability of the beam
What is the ideal BNR
1:1
What is an accepted BNR
2:1-8:1
Peak area of the maximum beam nonuniformity ratio (PAMBNR)
the area of the sound head covered by the peak intensity
Larger PAMBNR means what
less uniform heating
What is an ideal conducting media for US
US gel and gel pads
Indirect ultrasound is
ultrasound done underwater in a plastic bucket
keep sound head parallel 0.5-3.0 cm
Amplitude of soundwave
more watts=more heating NOT GREATER PENETRATION
frequency of US
1-3 MHz
Does high or low frequency absorb more rapidly
high (3MHz)
superficial tissue
does high or low frequency absorb slower
low (1MHz)
deep tissue
higher density leads to _______ absorption rate
higher
Effects of US
Inc extensibility
Inc blood flow
Inc healing
Dec stiffness/spasm
Non thermal effects
pulse US- alters cellular activity for injury repair
What is stable cavitation
rhythmic expansion and contraction of bubbles during repeated pressure changes over many acoustic cycles
What is unstable cavitation
collapse of gas bubbles which may cause tissue damange (low frequency high intensity US)
Contraindications of US (12)
malignancy hemmorrhage ischemia thrombus infection gonads eye pelvic/lumbar/abs of preggo spinal cord post laminectomy plastic and cemented implants electronic implants unknown etiology
What type of implants are okay for US
metal
Where should you avoid with US (2)
bony prominences
epiphyseal plate
What size is the treatment area for US
2-3x the size of ERA
How long is treatment with US
5-8 min
NEVER LONGER THAN 15 MIN
What is phonophoresis
sonophoresis
uses sound energy to drive medication into tissue
What is LIP US
low intensity pulsed US
stimulation of fracture healing
what is NCLF US
noncontact low frequency US
wound cleaning and debridment
