Ultrasound Flashcards
Can we as humans hear the sounds that ultrasound gives off?
no
what does ultrasound do?
it has a deep heating modality that penetrates skin and subcutaneous fat
it is used to heat muscles, tendons, ligaments, joints capsules and scar tissues
it also has non thermal mechanical effects
can ultrasound heal bone fractures?
slowly, in low intensities
can ultrasound help heal wounds?
yes, when it is non-contact, low frequencies
what is the most common use for ultrasound among chiropractors?
deep heating modality
what is the second most common heating modality in the US?
ultrasound
How does ultrasound work?
an electrical current is passed through a crystal causing it to vibrate
this causes soundwaves to be generated
crystal is usually what kind of material?
quartz, lead zirconate, lead titanate, barium titanate, nickel colbalt ferrite about 2-3mm in thickness
what is the duty cycle of ultrasound?
divide time sound is delivered by total treatment time
continuous vs pulsed?
continuous- 100%
pulsed- 20-50%
piezoelectric effect
mechanical deformation of a crystal causes an electrical current to form
reverse piezoelectric effect
alternating current is passed through a crystal
results in very fast contraction and expansion of the crystal
vibration produces high frequency sound waves
why must ultrasound have well insulated cables?
because it requires a high voltage
another name for near field? What is the near field?
fresnel zone
treatment area
another name for farfield?
Fraunhofer zone
what are the coupling agents used with ultrasound?
gel
gel pad
tap water
spatial peak intensity
maximum intensity delivered during continuous ultrasound energy
spatial average intensity
average intensity delivered during pulsed delivery of ultraound energy
ERA
effective radiating area
area of the sound head that produces sound energy
always smaller than the size of the ultrasound heat
BNR
beam nonuniformity ratio
amount of variability of the beam
ratio between the peak intensity of the ultrasound beam divided by the average intensity of the ultrasound beam
used to compare quality of different machines