Ultrasound

Question 1

What is Ultrasound

Answer 1

accoustic energy due to alternating compressing and rarefying potential

> 20Mhz, inaudible to human ears

Question 2

How is it generated: Generator

Answer 2

electric

Oscillator circuit produces high frequency

Question 3

How is it generated: Crystal

Answer 3

synthetic
uniform beam
Transducer

Question 4

Transducer

Answer 4

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

Question 5

How is it generated: sound head

Answer 5

transfers accoustic tissue

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

Question 6

Applicator

Answer 6

houses crystal and sound head
held by PT
hard insulated plastic

Question 7

Electromagnetic vs. Mechanical

Answer 7

electromagnetic- protons move along wave

mechanical- molecules bump into neighbor, propagating energy

Question 8

Mechanical longitudinal wave

Answer 8

microstreaming

along the direction the wave travels, liquid/gases

Question 9

Mechanical transverse wave

Answer 9

perpendicular to the direction traveled

solid

Question 10

Spatial

Answer 10

size of transducer

Question 11

Spatial Average Intensity

Answer 11

power/ERA= W/cm2

Question 12

Spatial Peak Intensity

Answer 12

generally over center

Question 13

Spatial Average Temporal Peak

Answer 13

when SAI is on

Question 14

Spatial Average Temporal Average

Answer 14

STAPx duty cycle, measures what is delivered to tissue

Question 15

Beam Nonuniformity Ratio

Answer 15

spatial peak intensity: spatial average intensity

Question 16

Frequency

Answer 16

0. 75 Mhz up to 5 cm
1. 3 Mhz up to 2 cm

higher frequency= higher absorption

Question 17

Absorption

Answer 17

mechanical to kinetic

decibals/cm

Question 18

Absorption depends on?

Answer 18

tissue type and intensity

collagen= more absorption
more intense= more absorption

Question 19

Absorption ranking

Answer 19

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

Question 20

Reflection

Answer 20

reflected 100% in air

0.1% with couplant

Question 21

Refraction

Answer 21

wave enters @ 1 angle, continues @ another angle

Question 22

Attenuation

Answer 22

measures decrease in intensity as wave travels through tissue

Question 23

Standing wave

Answer 23

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

Question 24

Cavitation

Answer 24

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

Question 25

Contraindications of T.U.S

Answer 25

``` malignancy/tumor pregnancy CNS tissue recently radiated tissue cemented joint/replacement ``` ``` pacemaker thrombophlebitis eyes, ear, genitals infection active hemorraging ```

Question 26

Factors that affect TTR

Answer 26

rate duration themal conductivity rate of perfusion of blood to tissue

Question 27

Non thermal effects of T.U.S

Answer 27

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 ```

Question 28

T.U.S Clinical Uses

Answer 28

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

Question 29

Precautions

Answer 29

acute inj growth plates breast implants fractures

Question 30

Velocity depends on

Answer 30

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