UltraSound Flashcards
(45 cards)
When is 1 mHz absorbed? US
5-7 cm
when is 3 mHz absorbed? US
3 cm
What would you use for deep muscles? US
1 mHz
what would you use for superficial muscles? US
3 mHz
Which frequency will heat the fastest? US
3 mHz
How is US treatment time calculated?
treatment time is 2x ERA
10cm2 ERA = Rx time would be 5-10 min
What is the beam non-uniformity ratio?
ratio between the transducers peak intensity and spatial intensity
smaller ratios mean beam is more uniform
should be 6:1
what is spatial average intensity?
avg intensity of the US output over area of transducer
what is spatial peak intensity?
peak intensity over area of transducer
Attenuation rates
Blood-3
Fat-13
Muscle-24
Blood vessel-32
Skin-39
Tendon-59
Cartilage-68
Bone-96
Where is peak beam? US
Central third of ERA
What is the reverse piezoelectric effect?
Crystal is compressed and expanded by sending SC through it which causes a compression and expansion of the crystals
Does intensity have anything to do with depth of penetration?
No
How is frequency and depth penetration related
Inversely proportional
Spatial avg intensity equation
Power (watts)/ ERA (cm2)
What duty cycle is used for pulsed US?
20 %
How is duty cycle calculated ?
Duration of pulse (time on)/ pulse period(time on +time off)
How do you get significant US heating ?
US must be applied to an area 2x the size of ERA
vigorous heating
increase of about 7 deg
will result in increase distensibility
what is the insurance cap for US
8 min
1mhz heat 6 F
11 min
3mHz heat 6F
6 min
max US treatments
2-3xweek
10-15 treatments
effects of thermal US
-increased collagen extensibility
-increase blood flow
-decrease pain
-reduction of Muscle spasms
-decrease joint stiffness
-reduction of chronic inflammation
