chapter 7. ultrasound - kocwcontents.kocw.net/kocw/document/2014/cu/shinhwakyung/1.pdf · 2016. 9....
TRANSCRIPT
CHAPTER 7. ULTRASOUND
Introduction
2
Definition of ultrasound3
Ultrasound
all forms of sound consist of waves that transmit energy by alternately compressing and rarefying material
US > 20,000 Hz
Therapeutic US : 0.7 ~ 3.3 MHz to maximize absorption at depth of 2 to 5 cm of soft tissue
※ Decreasing ultrasound intensity as the wave travels through tissue
Effects of US4
Thermal effect : continuous US heats tissue with a high collagen content
.
Non-thermal effect : low-intensity pulsed ultrasound facilitate tissue healing
modify inflammation
enhance transdermal drug delivery
Mechanism acoustic streaming microstreaming, cavitation
Definition of US 5
US effect
Thermal effect
non-thermal effect : acoustic streaming, microstreaming, cavitation
Absorption 6
Absorption
Absorption of US : Conversion of the mechanical energy of US into heat
↑Absorption coefficient : ↑collagen content, ↑ US frequency
Acoustic streaming7
Acoustic streaming
The steady, circular flow of cellular fluids induced by US
larger in scale than with micro-streaming
→ alter cellular activity by transporting material from one part of
the US field to another
Attenuation
Attenuation
The decrease in US intensity as US travels through tissue
US is attenuated in the tissue by Absorption, Reflection Refraction
Attenuation is greatest in tissues with a high collagen content and with the use of high US frequencies→ Attenuation coefficient is tissue and frequency- specific (table 7-1)
Generation of US
Alternate current
↓
piezoelectric crystal
(Crystal contracts and expands)
↓
US is generated
Ultrasound production by piezoelectric crystal
Thermal effects Non-thermal effects
Effects of US
10
Effects of Ultrasound 11
Continuous US Thermal effect
Pulsed US non-thermal effect
Small brief heating effect non-thermal effect also increase the temperature of deep and superficial
tissue
Thermal effects Tissue affected12
Same as other heating modality, except the structure heated
US reaches more deeply and heats smaller areas than most superficial heating agents
US는 high US absorption coefficients 를 가진 조직을 heating
→ high collagen content ex. Tendon, ligament, joint capsule, fascia
US can be very effective for heating small area of scar tissue in muscle that will likely absorb more US (∵ increased collagen content of scar tissue)
Factors affecting the amount of temperature increase
Tissue to which the US is applied
Frequency
Average intensity
Duration
cf,. speed of transducer X
Thermal effects Factors affecting the amount of temperature increase
13
14
Tissue absorption coefficient
Rate of tissue heating by US is proportional to
Tissue absorption coefficient (collagen content) at the applied US frequency
Thermal effects Factors affecting the amount of temperature increase
Thermal effects Factors affecting the amount of temperature increase
15
Temperature distribution for 1 and 3 MHz ultrasound at the same intensity.
Frequency controls the depth of penetration of ultrasound; 1 MHz ultrasound penetrates approximately 3 times as far as3.3 MHz ultrasound
2. US frequency
16
3 MHz
maximum temperature high, penetration depth low
1~2cm 깊이의 heating tissue에 best
1 MHz
5cm 깊이까지의 heating tissue에 best
3MHz 는 1MHz보다 3~ 4배 온도를 증가시킬 수 있다 ( in 1~2 ㎝ deep)
그러므로 임상 적용 시, 1MHz를 적용할 때 보다 3MHz를 적용할 때 3~4 배 적은 intensity가 사용되어야 한다.
Thermal effects Factors affecting the amount of temperature increase
17
Duration and intensity of US
to increase the total amount of energy being delivered the tissue
Other factors heating the tissue
Blood circulation through tissue : cooling of tissue
Conduction from one warmed area of tissue to another
Reflection of US wave in region of soft tissue – bone interface
Thermal effects Factors affecting the amount of temperature increase
18
Moving the sound head through the application
: helps to equalize the heat distribution and minimize causing excessively hot or cold area
The patient’s report of warmth is used to determine the final US intensity when applying thermal-level US
US intensity very high : complain of a deep ache form overheating of the periosteum
very low : not feel any increase in temperature
Thermal effects Factors affecting the amount of temperature increase
Thermal effects Applying other physical agents in conjunction with US19
Hot pack before US
: deep tissue의 온도 증가에는 영향 미치지 않음
Heating (39 °C) or cooling (18°C) the conduction medium
: decrease the rate of heating with US with the faster rate of heating occurring with slightly warm(25 °C)
Applying US in cold water
: cool the superficial by conduction and convection
Applying ice before the application of US
: reduce the temperature increase produced by US in the deeper tissue
Nonthermal effects 20
Pulsed US with a 20% duty cycle
Cavitation, acoustic streaming, microstreaming
US with low average intensity
↑ intracellular calcium levels↑ skin and cell membrane permeability ↑ normal function of a variety of cell type ↑ mast cell degranulation and their release of chemotactic factor
and histamine↑macrophage responsiveness↑the rate of protein synthesis by fibroblast and tendon cell ↑ nitric oxide synthesis in endothelial cell ↑ blood flow when applied to fractures in dog and to ischemic muscle in
rats ↑ stimulate proteoglycan synthesis by chondrocyte (cartilage cells)
Soft tissue shortening
Pain control
Dermal ulcers
Surgical skin incisions
Tendon and ligament injuries
Resorption of calcium deposit
Bone fracture
Carpal tunnel syndrome
Phonophoresis
Clinical applications of US
21
Soft tissue shortening
Soft tissue temperature ↑
Soft tissue temperature ↑
Extensibility↑Extensibility↑
Length gained for the same
force of stretch ↑
Length gained for the same
force of stretch ↑
Risk of tissue damage ↓
Risk of tissue damage ↓
Altered viscoelasticity of
collagen & collagen matrix
Altered viscoelasticity of
collagen & collagen matrix
Increased length is maintained
more effectively
Increased length is maintained
more effectively
Immobilization
Inactivity
Scarring
Soft tissue
shortening
ROM restrictions
Pain
Functional limitations
Soft tissue shortening 23
Effective Tx. Parameters• Continuous US
• 1 or 3 ㎒ frequency (depending on the tissue depth)
• 0.5~1.0 W/㎠ intensity when 3 ㎒ frequency
• 1.5~2.5 W/㎠ intensity when 1 ㎒ frequency
• 5~10 min.
• Stretching be applied during heating &
maintained for 5~10 min. after US
Joint capsules, tendons, ligaments
→ High US absorption coefficients
∴ US can be effective for heating these tissues
Soft tissue shortening 24
Ultrasound being applied to the posterior knee in conjunction with an extension stretching force.
Pain control
Pain control - By altering its transmission or perception - By modifying the underlying condition causing pain
the results of - stimulation of the cutaneous thermal receptor or increased soft tissue
extensibility caused by increased tissue temperature - changes in nerve conduction caused by increased tissue temperature or
nonthermal effects of US - Modulation of inflammation caused by nonthermal effect of US
Effective Tx. Parameters• Continuous US• 1 or 3 ㎒ frequency (depending on the tissue depth)• 0.5~3.0 W/㎠ intensity• 3~10 min.
Dermal ulcers 26
Some studies have shown that US accelerates the healing of vascular and pressure ulcer
Others have failed to demonstrate any beneficial effects with this application• Pulsed US may facilitate wound healing but good
evidence of this effect is lacking
Application of US to dermal ulcer - periwound application technique - treat directly by covering it with an US coupling sheet - underwater application technique
standard of care + noncontact kilohertz US
27
periwound application technique Ultrasound being used to treat a venous stasis ulcer
underwater application technique
Effective Tx. Parameters Pulsed US
20% duty cycle
3 ㎒ frequency
0.8~1.0 W/㎠ intensity
5~10 min.
Applying to
- Intact skin around the wound perimeter
- Treated directly by covering with an US coupling sheet
- US transducer in water
A noncontact ㎑ US device
40 ㎑ frequency
0.1~0.5 W/㎠ intensity
5~15 ㎜ from the wound
Tx. duration- 3 min. (wound that is less than
10 ㎠)
- 4 min. (wound that is 10~19 ㎠)
- time increases by 1 min. for each further 10 ㎠ increment
Dermal ulcers
Surgical skin incisions 29
US can - accelerate the healing of surgical incision
- Relieve the pain associated with these procedures
- Facilitate development of strong repair tissue
Earlier intervention was recommended for earlier relief of
symptoms
Effective Tx. Parameters Pulsed US
20% duty cycle
0.5~0.8 W/㎠ intensity
3~5 min., 3~5 times a week
Tendon and ligament injury
Pulsed US
• Low intensity(0.5~1.0 W/㎠)
• Acute phase of tendon inflammation
Continuous US
• High enough intensity
- to increase tissue temperature
• Chronic tendinitis
- with stretching (if the problem is accompanied by soft tissue shortening)
Effective Tx. Parameters to tendon healing
• Pulsed or continuous US
• 1 or 3 ㎒ frequency
• 0.5~2.5 W/㎠ intensity
• 3~5 min.
Effective Tx. Parameters to ligament healing
• Pulsed US, low dose(0.5~1.0 W/㎠) intensity
Tendon and ligament injury 31
US should be applied
- in a pulsed mode at low intensity for acute tendinitis
- in a continuous mode at higher intensity along with stretching for chronic tendinitis
Resorption of calcium deposit 32
To facilitate the resorption of calcium deposits
: But mechanisms of this effect are unknown
Figure 07-08. Fracture healing 17 days postoperatively. A, with, and B, without ultrasound application.
Bone fracture 33
The use of very low dose US for facilitate of fracture healing
Treatment parameter
: 1.5 MHz frequency, 0.15 W/㎠ intensity, 20% duty cycle, for 15~20 min.
In 34
Figure 07-09. Ultrasound device for home use for fracture healing
Carpal tunnel syndrome35
Anti-inflammatory and tissue stimulating effects
Phonophoresis36
US increase transdermal drug penetration
By increasing the permeability of the stratum corneum through cavitation
: both thermal and non-thermal mechanism
permeability of the stratum corneum ↑
→ diffusion of drug across stratum corneum(∵ difference in concentration)
→ initially more concentration at the delivery side and is then distributed throughout the body by the vascular circulation
contraindications for systemic delivery of these drugs 일 경우?
37
Figure 07-10. Layers of the skin
Phonophoresis38
다른 route로 약물을 투여하고 있다면, 같은 drug를 phonophoresis 해서는 안된다. ∵ increase the risk of adverse effect(역효과)
20~ 100 kHz (i.e. much lower than typically used in therapy)
→ skin permeability ↑↑
US for facilitation of transdermal drug penetration
pulsed 20% dyty cycle, 0.5~0.75 W/㎠ intensity, 5~10 min
Contraindications and precautions for the use of US
39
Contraindications and precautions for the use of US
Malignant tumor
Pregnancy
CNS tissue
Joint cement
Plastic component
Pacemaker
Thrombophlebitis
Eyes
Reproductive organs
Precautions for the use of US 41
Acute inflammation
Epiphyseal plates
Fracture
Breast implants
Adverse effects of US 42
Burn - high intensity, continuous US, stationary application technique - In areas with impaired circulation or sensation and with superficial
bone - To minimize the risk, moving the US head
US standing wave can cause blood cell stasis - : collections of gas bubbles and plasma at antinode and collection off
cells at node. - Damage to endothelial lining of the blood vessels - US transducer should be moved throughout treatment application
cross-contamination and infection of patients : clean with 70% alcohol
43
Figure 07-11. Banding of blood cells and plasma due to standing waves
Ultrasound treatment parameters
Application technique
44
Frequency
According to the depth of tissue
- 5 ㎝ deep : 1 MHz
- 1~2 ㎝ deep: 3 MHz
the depth of penetration is lower
- in tissue with a high collagen content.
- in areas of increased reflection
Duty cycle 46
According to treatment goal
- Thermal effect : 100% (continuous) duty cycle
- Non-thermal effect : pulsed US with a 20% or lower dyty cydle
Intensity 47
According to treatment goal
Thermal effect
- US 적용 후 2~3mim 내에 환자는 온열감을 느껴야 하고, 치료 동안 increased discomfort를 느껴서는 안된다.
- 1 MHz : 1.5 ~2.0 W/㎠
- 3 MHz : 0.5 W/㎠( ∵lower intensity is effective at the higher frequency)
- Patient’s report에 따라 intensity 조절
: 2~3min 내에 온감을 느끼지 못하면 intensity ↑, 불편함을 느낀다면 즉시intensity ↓
- Treatment area에 superficial bone이 있다면, slightly lower intensity가comfortable heating을 생산하기에 충분하다.
(∵bone에 의해 반사된 US는 더 큰 온도 증가를 나타낸다)
Intensity48
US for non-thermal effect
- intensity of 0.5 ~1.0 W/㎠ SATP (0.1~0.2 W/㎠ SATA),
With as low as 0.15 W/㎠ SATP (0.03 W/㎠ SATA) sufficient for facilitation of bone healing
Beam non-uniformity ratio(BNR) 49
Beam non-uniformity ratio(BNR) spatial peak intensity : the spatial average intensity
Usually 5:1 ~ 6:1 ex. Maximum BNR of 5 : 1 이라면? spatial average intensity 1 W/ ㎠ , spatial peak intensity 5 W/ ㎠
50
Spatial average intensity (SAI)
Spatial average temporal average (SATA) intensity : on off time
Spatial average temporal peak (SAPT) intensity
Spatial peak intensity
Duration 51
According to
- treatment goal
- size of the area to be treated
- the ERA of the sound head
Duration for most thermal and non-thermal application
- 5~10 min for each treatment area that is twice the ERA of the transducer
i.e. When treating an area 20㎠ with a sound head that has an ERA
of 10 ㎠, the treatment duration should be 5~10 min
Q. When treating an area of 40㎠ with the same 10 ㎠, the treatment
duration should be extended to ( min.)
Duration52
Thermal effect : adjust according to the frequency and intensity of
the US
Example
- tissue temperature ↑ by 3°C
(→minimal therapeutic level of 40 °C )
1 MHz US at an intensity of 1.5 W/㎠, an area twice the ERA of the transducer.
→ treatment duration at least 9min,
- whereas if the intensity is increased of 2 W/㎠, the treatment duration 8 min.
- 3 MHz, 0.5 W/㎠, treatment duration at lest 10 min. to achieve the same temperature level.
Duration53
Treatment duration을 증가시켜야 하는 경우?
- lower intensities or lower frequencies 가 사용되었을 때.
- Treating area가 ERA이 2배보다 더 클때
- Higher tissue temperature를 원할때
US for facilitating bone healing
: longer treatment times if 15~20 min
Area to be treated 54
According to
- ERA of the transducer
- Duration of treatment
Treatment area equal to twice the ERA of the sound head
- 5~10 min.
ERA의 4배 이상의 treatment area는 안됨.
ex, whole lower back
55
Figure 07-12. Ultrasound application to the foot
56
Figure 07-13. Ultrasound application to the temporomandibular joint (TMJ) area
Number and frequency of treatment57
Thermal level US
- Subacute or chronic phase of healing
- 3 times a week
Non-thermal level
- earlier stage
- Frequent as daily
Sequence of treatment58
Thermal US
- When using US to heat tissue, it should not be applied after any intervention that may impair sensation, such as ice..
- before, and if possible during, the application of the stretching force
- Should not apply another intervention between US and stretching
(∵ )
Moving the sound head 59
4㎝/sec
- Too slowly
- Too quickly
Strokes overlapping by half the ERA of the sound head
Keep contact parallel contact with the skin
- poor contact?
- Transmission sensor
60
Figure 07-13. Ultrasound application to the temporomandibular joint (TMJ) area
Documentation
61
Documentation
Area of the body treated
US frequency
US intensity
US duty cycle
Treatment duration
Whether the US was delivered under water
Patient’s response to the intervention
Example by SOAP
63
Figure 07-15. Decision-making chart for ultrasound treatment parameters
Absorption 64
Absorption of US
: Conversion of the mechanical energy of US into heat
↑Absorption coefficient
- ↑collagen content, ↑ US frequency
- Table
Acoustic streaming 65
Acoustic streaming (음향 유동)
- The steady, circular flow of cellular fluids induced by US
- larger in scale than with micro-streaming
→ alter cellular activity by transporting material from one part of
the US field to another
Attenuation 66
The decrease in US intensity as US travels through tissue
Beam non-uniformity ratio(BNR) 67
spatial peak intensity : the spatial average intensity
Usually 5:1 ~ 6:1
ex. Maximum BNR of 5 : 1 이라면?
spatial average intensity 1 W/ ㎠ , spatial peak intensity 5 W/ ㎠
Cavitation68
The formation, growth, and pulsation of gas-filled bubbles caused by US
Stable cavitation – nonthermal therapeutic cavitation
Unstable cavitation- not to occure at the intensity of US used therapeutically
69
Figure 07-18. Longitudinal cross-section of an ultrasound beam.
70
Figure 07-19. Ultrasound reflection and refraction
71
Figure 07-20. Formation of standing waves
72
Figure 07-21A. Ultrasound units: 1, transducer; 2, power/intensity indicator.
73
Figure 07-21B. Ultrasound units: 1, transducer; 2, power/intensity indicator.
74
Figure 07-22. Continuous ultrasound.
75
Figure 07-23. Duty cycles: 20% and 50%
76
Figure 07-24. Effective radiating area (ERA).
77
Figure 07-25. Ultrasound frequencies: 1 and 3 MHz.
78
Figure 07-26. Frequency controls the depth of penetration of ultrasound; 1 MHz ultrasound penetrates approximately 3 times as far as 3.3 MHz ultrasound
79
Figure 07-27. Pulsed ultrasound
80
Figure 07-28. Spatial average temporal peak (SATP) and spatial average temporal average (SATA) intensity.
81
Unn Figure 07-01.
82
Figure 07-02.
83
84
85