Ultrasound

Question 1

○ Beyond 20,000 Hz
○ Cannot be heard (since ang hearing
range is from 15000-20000 Hz)
○ Limit between 1 Hz and 3 mega Hz for
therapeutic purposes

Answer 1

Frequency

Question 2

○ Distance between the 2 equivalent points
of the waveform in the particular
medium
○ 1 mega Hz on average tissue = 1.5 mm of
wavelength
○ 3 mega Hz = 0.5 mm

Answer 2

Wavelength

Question 3

○ refers to the speed of the wave as it
passes through the medium (differ based
on medium)
○ Passes through a saline solution – 1,500
m/sec
○ Waves travel on a more dense medium

Answer 3

Velocity

Question 4

○ longitudinal in wave form that contains
compression and rarefaction –
approximation and separation of waves
as it passes through a vacuum

Answer 4

Sound Waves

Question 5

● As electric current passes through the TUS, it
passes through a crystal
○ causing deformation and vibration
○ Electricity across the crystal causes
deformation and vibration

Answer 5

piezoelectric effect

Question 6

a crystal that produces
(+) or (-) electrical charges when it contracts or
expands

Answer 6

Piezoelectric crystal

Question 7

● A device that converts one form of energy to
another

Answer 7

Transducer

Question 8

○ area of the ultrasound beam on the
transducer used for therapeutic purposes
○ Beam emitted nearest to the transducer
head
○ Prone for hot spots due to focalization of the
beam (yang center ng blue beam)

Answer 8

Fresnal/Freznel (near field)

Question 9

○ located away from transducer head; beam is
more uniform (even heating) and gently
divergent; can also be used for therapeutic
purposes
○ Hotspots are not significant

Answer 9

Fraunhoffer’s zone (far field)

Question 10

● The average intensity of the US output over
the area of the transducer
● Intensity is the dosage on how much heat is
emitted within the transducer head

Answer 10

Spatial Average Intensity

Question 11

● The peak intensity of the US output over the
area of the transducer (middle)

Answer 11

Spatial Peak Intensity

Question 12

● The ratio of the spatial peak intensity to the
spatial average intensity
● Indication of near field interference in relation
to the amount of intensity produced

Answer 12

Beam Non-uniformity Ratio (BNR)

Question 13

continuos delivery of US all
throughout the
treatment period
● Generate
thermal effects

Answer 13

Continuous Ultrasound

Question 14

● Delivery of US during only a portion of the
treatment period
● Pulsing the US produces non-thermal effects
● Duty cycle – period of on and off time
● Generate non-thermal effect

Answer 14

Pulsed Ultrasound

Question 15

● The proportion of the total treatment time
that the US is on
● This can be expressed either as a
percentage or a ratio

Answer 15

Duty Cycle

Question 16

● The number of compression-rarefaction
cycles per unit time (1 sec)
● Frequency is inversely proportional to its
depth of penetration

Answer 16

Frequency

Question 17

● The area of the transducer from which the
US energy radiates

Answer 17

ERA

Question 18

The reduction of acoustical energy (US
intensity) as it passes through the soft
tissue
● Result of absorption, reflection, and
refraction

Answer 18

Attenuation

Question 19

– chance that there will be
reflection/refraction of the US; cause
periosteal burning (periosteum), causing pain

Answer 19

Cartilage and bone

Question 20

PHYSIOLOGICAL EFFECTS OF ULTRASOUND

Answer 20

Thermal

Question 21

which is the uneven
distribution of the acoustical energy
through the sound head

Answer 21

hotspot

Question 22

formation of gas filled bubbles within
the surrounding tissue and body fluids. Would
enhance the acoustic streaming

Answer 22

Cavitation

Question 23

the gas filled void/bubbles
would occur at therapeutic doses of ultrasound,
the bubbles would accumulate in the tissue/body
fluids

Answer 23

Stable Cavitation

Question 24

• There is vibration or
  production of movement of particles/fluids near
  a vibrating structure, such as the cell membranes
  and body structures. This would cause an
  activation and may produce an effect to the cell
  membrane permeability and then affect the
  diffusion rates

Answer 24

Acoustic Streaming