first part

Explain the History of Ultrasound (sunod-sunod dapat)

19th century → WW2 → Sonar → Damage to marine life →

EUREKA → TISSUE HEATING

Ultrasound most effectively heats _____ with a _____ such as _____, _____, _____, and _____

deep tissue; high collagen

content; tendons; ligaments; joint capsules; fascia

Ultrasound has both _____ and _____ effects

thermal; non-thermal

Soundwaves that transmit energy by alternately ____

and _____ material

compressing; rarefying

Ultrasound has a frequency greater than _____

20,000 cycles/second (Hz)

Frequency of Therapeutic Ultrasound

•_____ to _____ to maximized energy absorption at a

depth of _____

0.7 to 3.3 MHz; 2 to 5 cm

What are the physical effects of ultrasound? (include the bpts)

Thermal

• increase in tissue temperature

Non-thermal

• Acoustic streaming

• Microstreaming

• Cavitation

Ultrasound Sound Wave can be described by:

• Intensity (w/cm2)

• Frequency (MHz)

• Duty cycle (%)

• Effective radiating area (ERA)

• Beam Nonuniformity Ratio (BNR)

unit of measurent of Intensity

(w/cm2)

unit of measurent of frequency

(MHz)

unit of measurent of duty cycle

(%)

The decrease in US intensity as it travels through tissue

Attenuation

Attenuation

• The _____ in US intensity as it travels through tissue

• decrease

Attenuation

• The decrease in US _____ as it travels through tissue

• intensity

Attenuation is _____ and _____ specific

tissue; frequency

As it enters the body, US is attenuated by:

Absorption

Reflection

Refraction

50% of attenuation; 50% of sound is

absorbed by tissues

Absorption:

no absorption, bounce back

• Reflection –

not absorbed by target tissue; bounces to

other areas

• Refraction –

Attenuation, dB/cm of blood

0.12

Attenuation, dB/cm of fat

0.61

Attenuation, dB/cm of nerve

0.88

Attenuation, dB/cm of muscle

1.2

Attenuation, dB/cm of blood vessel

1.7

Attenuation, dB/cm of skin

2.7

Attenuation, dB/cm of tendon

4.9

Attenuation, dB/cm of cartilage

5.0

Attenuation, dB/cm of bone

13.9

TRUE OR FALSE: When US is used in bones, it is more on for fracture healing

TRUE

When US is used in bones, it is more on for _____

fracture healing

The proportion of the total treatment time during which

ultrasound is being delivered

The duty percentage or the ratio of the on time to the total

cycle time

Duty Cycle

The proportion of the total treatment time during which

ultrasound is being delivered

Duty Cycle

The duty percentage or the ratio of the on time to the total

cycle time

Duty Cycle

TRUE OR FALSE: Higher duty cycle = more heat

TRUE

TRUE OR FALSE Higher duty cycle = less heat

FALSE; more heat*

• High Frequency AC (alternating current) – crystal of transducer

head is made of material with piezoelectric properties

• Crystal expansion – compression of material in front

• Crystal contraction – rarefies material in front

• Alternating compression – rarefaction à US wave

Generation of Ultrasound

crystal of transducer head is made of material with piezoelectric properties

• High Frequency AC (alternating current) –

crystal of transducer head is made of material with _____

piezoelectric properties

compression of material in front

• Crystal expansion –

• Crystal expansion –

compression of material in front

rarefies material in front

• Crystal contraction –

• Crystal contraction –

rarefies material in front

US wave is generated from?

• Alternating compression – rarefaction →

• The ratio of the highest intensity in the field to the spatial

average intensity

• Heat/hotness of US

• 5:1; 6:1; 2:1

Beam Nonuniformity Ratio (BNR)

• The ratio of the highest intensity in the field to the spatial

average intensity

Beam Nonuniformity Ratio (BNR)

• Heat/hotness of US

Beam Nonuniformity Ratio (BNR)

• 5:1; 6:1; 2:1

Beam Nonuniformity Ratio (BNR)

Label

Average

Peak

E.R.A diameter

These/this have/has high water content

Blood

Fat

Nerve

These/this are/is neutral

muscle

These/this have/has high collagen content

Blood vessel

Skin

Tendon

Cartilage

Bone

What is the %/cm of Blood

3

What is the %/cm of Fat

13

What is the %/cm of Nerve

0

What is the %/cm of Muscle

24

What is the %/cm of Blood vessel

32

What is the %/cm of Skin

39

What is the %/cm of Tendon

59

What is the %/cm of Cartilage

68

What is the %/cm of Bone

96