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Flashcards in Ultrasound Deck (30)
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1

What is Ultrasound

accoustic energy due to alternating compressing and rarefying potential

>20Mhz, inaudible to human ears

2

How is it generated: Generator

electric
Oscillator circuit produces high frequency

3

How is it generated: Crystal

synthetic
uniform beam
Transducer

4

Transducer

electric to accoustic energy
reverse pizoelectric effect
creates vibration @ frequency of oscillator circuit of generator
vibrating crystals causes sound head to vibrate

5

How is it generated: sound head

transfers accoustic tissue
ceramic, alum, stainless steel, must match crystal (not interchangeable)

6

Applicator

houses crystal and sound head
held by PT
hard insulated plastic

7

Electromagnetic vs. Mechanical

electromagnetic- protons move along wave

mechanical- molecules bump into neighbor, propagating energy

8

Mechanical longitudinal wave

microstreaming
along the direction the wave travels, liquid/gases

9

Mechanical transverse wave

perpendicular to the direction traveled
solid

10

Spatial

size of transducer

11

Spatial Average Intensity

power/ERA= W/cm2

12

Spatial Peak Intensity

generally over center

13

Spatial Average Temporal Peak

when SAI is on

14

Spatial Average Temporal Average

STAPx duty cycle, measures what is delivered to tissue

15

Beam Nonuniformity Ratio

spatial peak intensity: spatial average intensity

16

Frequency

0.75 Mhz up to 5 cm
3.3 Mhz up to 2 cm

higher frequency= higher absorption

17

Absorption

mechanical to kinetic
decibals/cm

18

Absorption depends on?

tissue type and intensity

collagen= more absorption
more intense= more absorption

19

Absorption ranking

(most) bone, cartilage, tendon, skin, mm, nerve, fat, blood, (least)

20

Reflection

reflected 100% in air
0.1% with couplant

21

Refraction

wave enters @ 1 angle, continues @ another angle

22

Attenuation

measures decrease in intensity as wave travels through tissue

23

Standing wave

reflected wave interact with wave in opps. direction, summation occurs, leading to pain

24

Cavitation

formation of bubbles
compression, bubbles compress
rarefaction, bubbles expand
stable cavitation- nonthermal effects of US
unstable cavitation not used therapeutically

25

Contraindications of T.U.S

malignancy/tumor
pregnancy
CNS tissue
recently radiated tissue
cemented joint/replacement

pacemaker
thrombophlebitis
eyes, ear, genitals
infection
active hemorraging

26

Factors that affect TTR

rate
duration
themal conductivity
rate of perfusion of blood to tissue

27

Non thermal effects of T.U.S

increase in: histamine, calcium, phagocytosis of macrophages, protein synthesis, cap density of ischemic tissue

tissue regeneration
wound healing
altered cell membrane
white blood cell to injured site
inc in fibroblast
vascular regeneration

28

T.U.S Clinical Uses

CT healing
superficial wound healing
pitting edema
bone healing
spasms
pain
ROM

29

Precautions

acute inj
growth plates
breast implants
fractures

30

Velocity depends on

properties of medium through it travels
fastest through collegen dense tissue
slowest through air