Therapeutic Ultrasound Flashcards
1
Q
Ultrasound
A
sound waves with frequencies higher than the upper limit of human hearing, typically above 20,000 Hz
located in the acoustical spectrum, beyond the range of human auditory perception
2
Q
key uses and concepts
A
Diagnostic Imaging
therapeutic tissue healing
tissue destruction
3
Q
Diagnostic Imaging =
A
sound waves are sent into the body, and the echoes are captured to create images of structures inside the body (such as organs, muscles, and tissues)
commonly used for visualizing organs, blood flow, and other soft tissues
4
Q
Therapeutic Effects
A
Thermal & Non-thermal effects
Continuous vs Pulsed
5
Q
Thermal Effects:
A
Ultrasound therapy can increase the temperature of tissues, promoting blood flow and tissue healing, and enhancing the elasticity of tissues.
6
Q
Non-Thermal Effects:
A
It can also stimulate cellular activity and promote healing through mechanical effects like cavitation and microstreaming, even without significant temperature changes.
7
Q
Continuous:
A
In continuous ultrasound, the sound waves are emitted without interruption, causing more thermal effects
This is used when the goal is to increase tissue temperature
8
Q
Pulsed:
A
In pulsed ultrasound, the sound waves are emitted in short bursts, which helps to minimize thermal effects and is used for non-thermal benefits like promoting tissue healing
9
Q
Therapeutic Applications:
A
Phonophoresis:
Ultrasound can be used to enhance the delivery of topical medications (such as anti-inflammatory drugs) into subcutaneous tissues
push medication deeper into the skin and tissues, improving its effectiveness
10
Q
transducer =
A
device that converts one form of energy into another
converts electrical energy into mechanical energy (sound waves) and vice versa
11
Q
Piezoelectric Crystal:
A
generates electrical charges when subjected to mechanical stress (e.g., expansion or contraction)
produces positive (+) and negative (-) charges depending on the direction of stress
12
Q
crystals used in ultrasound transducers:
A
typically made of materials like quartz, barium titanate, lead zirconate, or titanate
ability to undergo mechanical deformation when subjected to an electric field, which is essential for ultrasound generation
13
Q
Reverse (Indirect) Piezoelectric Effect:
A
alternating current (AC) is applied to the piezoelectric crystal, it causes the crystal to contract and expand rapidly
expansion and contraction of the crystal create vibrations that generate high-frequency sound waves
imaging and therapeutic purposes
14
Q
Ultrasound Production:
A
vibrations of the piezoelectric crystal are responsible for producing the ultrasound waves
frequency of these sound waves is typically in the range of 1–3 MHz for medical applications, which is much higher than the range of human hearing (20 kHz to 20,000 Hz)
15
Q
the ___ uses the reverse ___ to produce high-frequency sound waves by causing a piezoelectric crystal to vibrate when an alternating current is applied
A
transducer
piezoelectric effect
16
Q
Frequency =
A
number of times an event occurs in 1 second
expressed in Hertz or pulses per second
17
Q
Hertz (Hz):
A
number of cycles per second
One Hertz is equal to one cycle per second
18
Q
Megahertz (MHz):
A
larger unit of frequency
One Megahertz (MHz) equals 1,000,000 Hertz
19
Q
frequency determines =
A
how many times the ultrasound waves are generated (or the piezoelectric crystal vibrates) per second
20
Q
In medical ultrasound, the most common frequencies used are
A
1 MHz, 2 MHz, and 3 MHz
21
Q
Low Frequency =
A
(1 MHz):
Lower frequencies penetrate deeper into tissues
lower frequencies have longer wavelengths, which can travel further through the body before being absorbed or scattered
22
Q
Low-frequency ultrasound is ideal for :
A
imaging or treating deeper structures
23
Q
High Frequency =
A
(3 MHz):
Higher frequencies are absorbed by more superficial tissues, meaning they don’t penetrate as deeply but provide higher resolution for imaging closer to the surface
This is useful for imaging or treating tissues that are closer to the skin.
24
Q
Relationship Between Frequency and Wavelength:
A
F = 1/ℷ
frequency (F)
wavelength (ℷ)
ℷ wavelength of the ultrasound wave
25
Lower frequency →
longer wavelength → deeper penetration
26
Higher frequency →
shorter wavelength → less penetration but higher resolution
sound waves are absorbed in more superficial tissues (3 MHz)
27
1 MHz =
(low frequency) is used for deeper tissue penetration, ideal for imaging or therapeutic use on deeper structures
28
3 MHz =
(high frequency) is used for superficial tissues, providing better resolution but less depth of penetration
29
Influences on Transmission of Energy
Reflection
Refraction
Absorption
30
Reflection –
occurs when the wave can’t pass through the next density
Energy bounces back when the wave encounters a boundary between different densities
31
Refraction –
is the bending of waves because of a change in the speed of a wave as it enters a medium with a different density
wave bends as it enters a medium with a different density, affecting the path of energy
32
Absorption –
occurs by the tissue collecting the wave’s energy
tissue collects the energy, converting it to heat, which can have therapeutic effects
33
Attenuation
decrease in intensity (or strength) of an ultrasound wave as it travels through a medium
reduction occurs due to a combination of reflection, refraction, and absorption
As the ultrasound waves penetrate deeper into the body, their energy is gradually lost, which affects their ability to produce accurate images or achieve therapeutic effects
34
Attenuation increases as the ___ of the ultrasound increases
frequency
35
higher-frequency sound waves face more resistance due to:
molecular friction when traveling through tissues
As the waves have a higher frequency, they experience more energy loss as they try to pass through the medium
36
Molecular friction =
the internal resistance encountered by the sound waves as they interact with the molecules in the tissue
At higher frequencies, the molecules must "move" more rapidly to accommodate the passing wave, creating greater friction and more energy being absorbed by the tissue
37
US penetrates through tissue high in ___ & is absorbed in dense tissues high in ___
water content
protein
38
Higher frequency (3 MHz): This results in greater ___ by tissues =
absorption
particularly dense tissues (like muscle or bone), which limits how deeply the sound waves can penetrate.
However, higher frequencies provide better resolution for imaging superficial tissues.
39
Lower frequency (1 MHz): This allows the waves to penetrate ___ because =
deeper
it experiences less absorption, making it ideal for imaging or treating deeper tissues
However, the image quality is not as high as with higher frequencies
40
increase Absorption = ___ Frequency ___
increase
(3 MHz)
41
increase Penetration = ___ Absorption ____
decrease
(1 MHz)
42
increase Penetration = ___ Frequency + ___ Absorption ___
decrease
decrease
(1 MHz)
43
Tissues with high water content (like fat or blood):
Low absorption rate:
These tissues are less likely to absorb ultrasound energy, so sound waves can penetrate more deeply.
Fat, in particular, allows for deeper penetration of ultrasound waves because of its lower density and high water content.
44
Tissues with high protein content (like muscle, bone, or peripheral nerves):
High absorption rate: These tissues tend to absorb more of the ultrasound energy due to their higher protein content, which results in higher attenuation.
For example, bone absorbs ultrasound energy much more efficiently than fat or muscle, reducing the depth to which ultrasound can penetrate.
45
Muscle =
lies somewhere in between—its absorption rate is higher than fat but lower than bone.
It offers moderate penetration and resolution for therapeutic applications.
46
Higher frequency (3 MHz) results in ___ resolution but ___ penetration due to higher ___ in dense tissues.
better
less
absorption
47
Lower frequency (1 MHz) results in ___ penetration (especially in deeper tissues) but ___ resolution due to __ absorption.
better
lower
lower
48
Fat (high water content) =
low absorption, allowing deeper penetration
49
Bone (high protein content) =
high absorption, resulting in shallow penetration
50
Muscle =
moderate absorption, allowing moderate penetration
51
Tissues increase water content =
low absorption rate (fat)
52
Tissues increase protein content =
high absorption rate (peripheral nerve, bone)
53
increasing protein content gives increasing absorption:
worst to best
blood
fat
nerve
muscle
skin
tendon
cartilage
bone
54
best absorption in:
tendon
ligament
fascia
joint capsule
scar tissue
55
Attenuation: Acoustic Impedance
resistance that a material presents to the passage of sound waves
depends on the density of the tissue and the speed of sound within that tissue
Z=density×speed of sound
56
The greater the acoustic impedance of a material, the ___ its resistance to sound waves
greater
57
If the acoustic impedance of the two materials at the interface is similar =
most of the ultrasound energy will pass through (i.e., transmit), and only a small portion will be reflected
58
If the acoustic impedances of the two materials are very different =
a larger portion of the ultrasound energy will be reflected, and less will be transmitted to the second medium
59
Air has a very ___ acoustic impedance compared to soft tissue
low
so when ultrasound waves try to pass through air (such as in a gel-free environment or on the skin’s surface), almost all of the energy is reflected
In fact, about 99% of the ultrasound energy is reflected back when trying to pass through air
60
Fat has a relatively ___ acoustic impedance compared to muscle or bone
low
so only about 1% of the energy is reflected, allowing ultrasound to pass through more easily
61
Bone has a very ___ acoustic impedance, and when soft tissue (such as muscle or skin) interfaces with bone, =
high
much of the ultrasound energy is reflected, making it difficult to use ultrasound for imaging or treatment in areas close to bone.
62
If acoustic impedance of the 2 materials forming the interface is the same =
all sound will be transmitted
63
The larger the difference =
the more energy is reflected & the less energy that can enter the 2nd medium
64
US passing through air =
almost all reflected (99%)
65
US through fat =
1% reflected
66
When ultrasound passes through tissue interfaces (such as between muscle and fat, or muscle and bone), some energy is ___, and some may also be ___, depending on the change in impedance between the materials.
reflected
refracted (bent)
67
Reflection occurs when =
the wave encounters a boundary with a significant impedance difference, such as between muscle and bone
68
Refraction occurs when =
the wave changes direction as it enters a new medium with a different impedance, often leading to distortions in image quality or energy delivery
69
Standing waves =
created when there is significant reflection of ultrasound energy at tissue interfaces, especially in areas with large differences in impedance (e.g., between soft tissue and bone)
70
When reflected ultrasound waves meet incoming waves, they create ___leading to areas of higher intensity, known as ___.
constructive interference
hot spots
71
hot spots can lead to =
localized heating of tissues
which is sometimes desirable for therapeutic ultrasound treatments (like in deep tissue heating), but can also be harmful if the energy is not properly distributed
72
The greater the impedance difference =
the more reflection occurs and the less energy enters the second medium
73
___ reflects almost all of the ultrasound energy, while ___ reflects much less, allowing for deeper penetration.
Air
fat
74
Effective Radiating Area (ERA):
portion of the ultrasound transducer (sound head) that actually produces ultrasonic waves
expressed in square centimeters (cm2)
75
The ERA represents:
the portion of the head’s surface area that produces US waves
76
ERA Measurement:
measured 5 mm from the face of the sound head and includes only the areas that produce more than 5% of the maximum power output
77
The ERA is always smaller than the ____
actual size of the sound head
because not all of the head’s surface produces ultrasonic waves at significant intensities
78
ERA Impact on Treatment:
ERA defines the actual area that is being treated by the ultrasound, influencing how much tissue is being impacted by the therapy
A larger ERA can treat a larger surface area more efficiently
79
Large Diameter Sound Heads:
tend to produce a column-shaped beam
energy is more concentrated along the central axis of the beam
remains focused over a longer distance
often used for larger treatment areas
80
Small Diameter Sound Heads:
create a more divergent beam
energy spreads out more as it moves away from the sound head
typically used for smaller, more targeted areas or for superficial tissues
81
Beam Divergence with Frequency:
Low Frequency (1 MHz)
High Frequency (3 MHz)
82
Low Frequency (1 MHz) ultrasound waves
tend to diverge more than higher frequencies
This means the energy will spread out more and affect a larger area, but with less intensity over distance
83
High Frequency (3 MHz) ultrasound waves
have less divergence, resulting in a more focused beam that is better suited for treating smaller, more superficial areas, but with greater energy concentration over a smaller area
84
Treatment Duration:
time the ultrasound is applied to the target area
depends on:
- i power output
- area of the treatment
- intensity
- desired therapeutic effect
85
Typically, therapeutic ultrasound treatments last ___ but this can vary based on the type of treatment being applied (e.g., for pain relief, muscle relaxation, or tissue healing).
between 5 to 10 minutes
86
Power (W)
total amount of energy produced by the ultrasound transducer
Measured in watts (W)
represents the overall energy output of the ultrasound device but does not account for how that energy is distributed across the treatment area
87
Intensity (W/cm²)
strength of the sound waves at a given location within the tissues being treated
measured in watts per square centimeter (W/cm²)
represents the amount of energy delivered to a specific tissue area
influences the therapeutic effects of ultrasound (e.g., deep heating, cavitation, tissue healing)
88
Key Intensity Measurements
Spatial Average Intensity (SAI)
Spatial Peak Intensity (SPI)
89
Spatial Average Intensity (SAI)
average amount of ultrasound energy passing through the effective radiating area (ERA) of the sound head
Expressed in W/cm²
used to determine the general intensity applied to the tissues
SAI = power/ERA
90
Spatial Peak Intensity (SPI)
maximum power output produced within the ultrasound beam
ultrasound beam is not uniform in intensity
certain areas within the beam may have higher intensity (hot spots)
risk of tissue damage in poorly controlled ultrasound treatments
91
Beam Nonuniformity Ratio (BNR)
Ratio between the spatial peak intensity (SPI) to the average output as reported on the unit’s meter
differences between SAI and SPI
92
Higher SPI & poor BNR =
increased risk of uneven heating and tissue damage
hot spots, leading to potential discomfort or tissue damage
93
The lower the BNR =
the more uniform the beam is
94
A BNR greater than ___ is unsafe
8:1
95
Because of the existence of high-intensity areas in the beam (hot spots), it is necessary to keep the US head ___
moving
96
Duty Cycle
percentage of time that the ultrasound (US) waves are actively emitted from the transducer (head) during treatment
important factor in determining whether the treatment has thermal or nonthermal effects
97
Duty Cycle ratio =
Ratio between the US’s pulse length & pulse interval when US is being delivered in the pulsed mode
98
duty cycle formula
Duty cycle = pulse length/(pulse length + pulse interval) x 100
99
Pulse Length:
The duration when the ultrasound is ON
100
Pulse Interval:
The duration when the ultrasound is OFF between pulses
101
The duty cycle is expressed as ___
a percentage (%)
102
100% duty cycle indicates =
constant US output
103
Low output produces ____
nonthermal effects (20%)
104
Continuous Mode (100% Duty Cycle) →
Thermal Effects
105
100% duty cycle =
ultrasound is continuously emitted without interruptions
Increased tissue temperature
Enhanced blood flow
Increased collagen extensibility
Decreased muscle spasms
Used for chronic conditions requiring deep tissue heating
106
Pulsed Mode (<100% Duty Cycle) →
Nonthermal Effects
107
Lower duty cycles =
(e.g., 20%, 50%) mean the ultrasound is delivered in pulses, allowing for periods of rest between emissions
reduces heat buildup
Cellular repair & tissue healing
Increased cell membrane permeability
Reduction of inflammation & swelling
Commonly used for acute injuries or tissue repair
108
20% duty cycle →
Primarily nonthermal effects, used for acute injuries & inflammation
109
50% duty cycle →
A mix of mild heating and nonthermal effects
110
100% duty cycle →
Strong thermal effects, used for chronic conditions
111
Coupling Methods =
ultrasonic energy cannot pass through air, a coupling medium is required to facilitate the transmission of sound waves from the transducer to the target tissue
112
Why is a Coupling Medium Needed?
Ultrasound waves require a dense medium to travel effectively
Air creates nearly 100% reflection, preventing energy from reaching the tissues
minimizing reflection and refraction at tissue interfaces
113
Why Should the Coupling Medium Be Water-Based?
Have low acoustic impedance, allowing for better energy transmission
Minimize wave reflection, ensuring more ultrasound energy enters the tissue
Are non-greasy, easy to apply, and do not degrade the transducer surface
Are safe for the skin and do not cause irritation compared to oils or lotions
114
Different coupling techniques are used based on:
body contour, treatment area size, and patient comfort
115
Direct Contact Coupling (Most Common)
Gel or Creams
water-based gel is applied between the transducer and the skin
Apply liberally to area - Remove air bubbles by passing sound head over area (before power is increased)
transducer maintains firm, continuous contact with the skin
Best for: Flat or moderately contoured areas (e.g., quadriceps, biceps, back)
Move the transducer in slow, circular or linear motions to prevent hot spots
116
Direct Coupling - move the head:
slowly
4 cm/sec
Move in circles
Moving the head faster decreases heating
If the patient describes discomfort, decrease the output intensity
117
Water Immersion Coupling (For Irregular or Small Areas)
treatment area is submerged in (degassed) water, with the transducer held 1inch away from the skin
ultrasound waves travel through the water, which acts as the coupling medium
Best for: Small, irregular areas (e.g., hands, feet, fingers, ankles).
Use a plastic or ceramic container (not metal, to avoid sound wave interference)
Keep the transducer slightly angled to minimize air bubble formation, which can block transmission
118
Immersion Technique - If tap water is used:
increase the output intensity by 0.5 w/cm2
119
Bladder or Gel Pad Method (For Bony or Highly Contoured Areas)
water-filled or gel-filled pad (or a fluid-filled bladder) is placed between the transducer and the skin
maintains consistent contact over highly contoured areas where direct contact is difficult
Best for: Areas over bony prominences (e.g., elbows, knees, shoulders).
Apply gel on both sides of the pad to eliminate air pocket
Ensure consistent pressure during treatment
120
Pad (Bladder) Method:
Commercial pads
Self-made bladders
Conforms to the treatment area
Commercial pads help limit the size of the treatment area
121
Preparation Tips for Effective Coupling
Clean the treatment area to remove oils, lotions, or dirt that may interfere with transmission
Ensure the skin is hair-free (or use extra gel) to reduce air pockets that can reflect energy
Check for air bubbles in immersion or gel pad methods, as they can disrupt wave transmission
Adjust pressure to maintain optimal contact without causing discomfort
122
Water-based gel is preferred for direct contact due to
low impedance and effective transmission
123
US Indications:
Soft tissue healing & repair
Joint contractures & scar tissue
Muscle spasm
Joint Contracture
Post-acute reduction of myositis ossificans
Acute inflammatory conditions (pulsed)
124
US Contraindications:
Acute Conditions (Continuous Output)
Ischemic Areas or Impaired Circulation Areas
Tendency to Hemorrhage
Over/Around Eyes, Heart, Skull, or Genitals
Over Pelvic or Lumbar Areas in Pregnant or Menstruating Females
Cancerous Tumors
Spinal Cord or Large Nerve Plexus (High Doses)
Anesthetic Areas/Diminished Sensation
Stress Fracture Sites or Over Fracture Site Before Healing is Complete
Acute Infection
125
Acute Conditions (Continuous Output)
can exacerbate inflammation in acute conditions by increasing tissue temperature, which may worsen swelling or injury
pulsed mode ultrasound (non-thermal) should be used if necessary
126
Ischemic Areas or Impaired Circulation Areas
can increase circulation, but in areas with already compromised blood flow (e.g., ischemic tissue), it could lead to tissue damage or further decrease oxygen supply
127
Tendency to Hemorrhage
can increase blood flow, which could be harmful for individuals with bleeding disorders or areas prone to hemorrhage (e.g., recent trauma with internal bleeding)
128
Over/Around Eyes, Heart, Skull, or Genitals
can affect the eye due to the risk of thermal damage
can interfere with cardiac rhythms or cause electrical disturbance if applied near the heart
Skull bones reflect high-frequency sound waves, which can cause tissue damage
Genital area and reproductive organs are sensitive and are generally avoided in clinical ultrasound therapy
129
Over Pelvic or Lumbar Areas in Pregnant or Menstruating Females
can penetrate deeply and potentially affect fetal development when applied to the pelvic or lumbar areas during pregnancy
may increase blood flow and cause discomfort.
130
Cancerous Tumors
Malignant tumors are highly sensitive to thermal effects
potentially stimulate growth or cause metastasis by enhancing blood circulation and metabolic activity in cancerous tissues
131
Spinal Cord or Large Nerve Plexus (High Doses)
High-dose ultrasound can cause nerve damage in areas like the spinal cord or large nerve plexus
132
Anesthetic Areas/Diminished Sensation
(e.g., due to nerve damage or anesthesia)
increased risk of thermal injury because the patient may not feel discomfort or pain during the treatment
133
Stress Fracture Sites or Over Fracture Site Before Healing is Complete
Continuous ultrasound over a stress fracture or fracture site before the bone has fully healed can cause tissue damage or interfere with healing
important to avoid ultrasound therapy on the epiphysis (growth plates) of children and adolescents as they are still developing and sensitive to changes in tissue temperature
134
Acute Infection
can increase blood flow and promote tissue heating, which might spread infection to other areas of the body
avoided in areas with acute infections or pus formation
135
Thermal Effects: increases =
blood flow
sensory & motor NCV
extensibility of structures (collagen)
collagen deposition
macrophage activity
136
Thermal Effects: decreases =
joint stiffness
muscle spasm
pain
137
Nonthermal Effects:
cell membrane permeability
vascular permeability
blood flow
fibroblastic activity
edema
138
Non Thermal effects have been demonstrated in ____
vitro but not in vivo
139
Overall- scant evidence of efficacy for ___
non-thermal
140
nonthermal effects from US lead to:
Altered rates of diffusion across cell membrane
Stimulation of phagocytosis
Production of granulation tissue
Synthesis of protein
Tissue regeneration
141
Pulsed Ultrasound (Non Thermal)
Stimulates phagocytosis (assists w/ decrease of chronic inflammation) & increases # of free radicals (increases ionic conductance on cell membrane)
142
Cavitation:
formation of gas bubbles that expand & compress due to pressure changes in tissue fluid
143
Stable cavitation:
as bubbles expand during low-pressure (trough) phases and compress during high-pressure (peak) phases of the ultrasound wave
bubbles oscillate but do not collapse completely
144
Unstable (transient) cavitation:
bubbles collapse completely during the high-pressure peaks of the ultrasound wave, causing them to implode violently
collapse can result in localized tissue damage and the production of shock waves, which can lead to unwanted effects like cellular injury or inflammation
BAD
145
Pulsed ultrasound enhances the activity of:
macrophages, helping to reduce chronic inflammation and promote the healing of damaged tissues
146
Acoustical Streaming (Non-Thermal Effect)
occurs primarily as a result of stable cavitation
unidirectional flow of tissue fluids
in the area surrounding cell membranes
147
Key Features of Acoustical Streaming:
Facilitates passage of calcium potassium & other ions, etc. in/out of cells
Collagen synthesis, chemotactics secretion, increases update of calcium in fibroblasts, increases fibroblastic activity
148
Enhances Collagen Synthesis & Fibroblastic Activity =
facilitates the synthesis of collagen, which is essential for tissue regeneration and wound healing
particularly beneficial for healing connective tissues, such as ligaments and tendons
149
Chemotactic Secretion
promotes the release of chemotactic factors—molecules that help attract cells involved in the inflammatory and healing processes
supports the body's natural healing response by recruiting cells like macrophages, which are essential for clearing debris and promoting tissue repair
150
continuous US:
constant energy level throughout the treatment
151
pulsed US:
pulse period = 10 msec
pulse duration = 2 msec
periodic cessation of the energy flow, so no US is delivered for a period of time = 8 msec
152
Length of time depends on the:
Size of area
Output intensity
Goals of treatment
Frequency
153
Area should be =
no larger than 2-3 times the surface area of the sound head ERA
154
If the area is large:
it can divided into smaller treatment zones
155
When vigorous heating is desired, duration should be:
10-12 min. for 1 MHz
3-5 min. for 3 MHz
156
Generally a ___ treatment period
10-14 day
157
Vigorous heating =
defined as an increase of ~7°F (4°C)
shown to increase the extensibility of connective tissue in vitro
Many clinicians limit their US treatments to 5 to 10 minutes, and many insurance companies limit treatments to 8 minutes?????
158
However, using 1-MHz US (1.5 watts/cm2 at 2 × ERA), it takes ___ minutes to heat skeletal muscle to 6°F (3.5°C) and even longer for vigorous heating of 7°F (4°C).
11
159
More superficial muscles can be heated to 9.5°F (5.3°C) in ___ minutes using 3 MHz (1 W/cm2, 2 × ERA)
6
160
Treatment time formula
time = desired temperature change / rate of temperature increase
161
1 MHz characteristics:
beam profile: relatively divergent
depth of penetration: 5 or more cm
max heating rate: 0.2 C (0.36 F) per min w/cm2 SLOW
heat latency: retains heat twice as long at 3 MHz
162
3 MHz characteristics:
beam profile: relatively collimating
depth of penetration: 0.8 to 3cm
max heating rate: 0.6 C (1.1 F) per min w/cm2 FAST (3-4x faster than 1 MHz)
heat latency: retains heat half as long as 1 MHz
163
US likes collagen
collagen-rich tissues such as:
- tendons
- ligaments
- joint menisci
- superficial bone
- large nerve roots
- intermuscular fascia
- scar tissue
largely fluid filled tissues (fat) = "transparent" to heating effects
muscle = largely fluid filled - not well heated via ultrasound, but scar tissue within the muscle belly is
164
Stretch fast!
only about a 3-minute window after an US treatment
collagen-rich tissues (ie: tendons) have increased elasticity
combo of US immediately followed by passive stretching for best results
164
Depth of Tissue vs Frequency?
general rule:
1 MHz = Tissues ≥ 1” Deep (2.5cm)
3 MHz = Tissues ≥ 1” Deep (2.5cm)
165
How warm do you need?
mild - 1C
mod - 2 C
vig - 3-4 C
166
mild 1 C =
1.8 F
increase: reduces mild inflammation, accelerates metabolic rate
167
moderate 2 C =
3.6 F
increase: decreases muscle spasm, decreases pain, increases blood flow, reduces chronic inflammation
168
vigorous 3-4 C =
5.4 F +
increase: tissue elongation (with load applied), scar tissue reduction
169
Output Intensity – 1 MHz
At a 100% DC:
2 W/cm2 output
Approximately 10-14 min treatment is required to increase tissue temp 4°C
170
Output Intensity – 3 MHz
At a 100% DC:
2 W/cm2 output
Approximately 3-5 min treatment is required to increase tissue temp 4°C
