Therapeutic Utrasound In Physiotherapy- Dr Rohit Bhaskar

ULTRASOUND
THERAPY
©2020 Rohit Bhaskar 1

DEFINITION
©2020 Rohit Bhaskar
➢ Ultrasound is a mechanical vibration at
any frequency above the audible
sound range
➢ Ultrasound therapy (UST) is the application of
ultra frequency sound waves (1 – 3MHZ) to
tissues in order to promote healing and reduce
pain and swelling.
➢ Therapeutic Us used in physiotherapy ranges
from
0.5 to 5MHZ but most us machine are set at
1MHZ and/or 3MHZ
➢ Classified as a deep heating modality
2

Production of ultrasound
➢The inverse piezoelectric effect is used in
production of ultrasonic sound waves.
➢Examples of piezoelectic materials are
quartz,barium titanate and lead zirconate
titanate (PZT).
➢Application of high frequency alternating
current to the PZT crystal of the transducer
transforms the electrical energy into vibratory
sound wave (ultrasound)s
3

Transmission of US wave
5
➢Through solid, liquid and gases in form
of compression and separation of
molecule
➢Normally cylindrical and longitudinal in fashion
➢Velocity higher in materials of high density
➢Air 340 m/s, water 1410m/s, muscle 1540m/s,
Bone 3500m/s.
4

Properties of ultrasound beam
➢Reflection
➢Refraction
➢Absorption
✓ Passing through the tissue US energy is
dissipated = attenuation
✓ Half Value Distance = 4cm for 1MHZ and 2cm
for 3MHZ
✓ Acoustic Impedance(Z)
5

Depth of penetration
➢ 1MHZ= deeper tissues
at depth 3 to 5cm
➢ 3MHZ= superficial
Tissues at depth 1 to
2cm
➢ Depth of Penetration is
inversely proportional
to frequency
Near and Far Field
➢ Wave fonts from
different parts travel
different distances
causing interference
between adjacent
fonts
6

Near and far field
8
➢ The near field also
known as the
Fransel zone is the
convergent region
➢ The far field known
as the fraunhofer
zone is the
divergent region
➢ Length of Fresnel zone
= r2 / λ where r=radius
of transducer.
➢ Therapeutic us
utilizes the near
field
➢ Frequency of US and
radius of transducer
need to be considered
for tissue depth above
6.5cm(shortest)
7

Coupling media
9
Ultrasound waves are not transmitted by air,
thus some couplant which does transmit them
must be interposed
Unfortunately no couplant affords perfect
transmission & only a percentage of the
original intensity is transmitted to the
patient.
Aquasonicgel 72.6%
Glycerol 67 %
Distilled water 59 %
Petroleum jelly 0 %
Air 0 %
8

Characteristics of a coupling media
1
0
1. Acoustic impedance similar to
tissue
2. High transmissivity for US
3. Low suceptibility to bubble
formation
4. Chemically inactive in nature
5. A hypoallergic character
6. High viscosity
7. Cheap
8. Relative sterility
9

US beam parameters
➢ Mode type : continuous and pulsed. Pulsed Mark
Space(M:S) ratio: 1:1, 1:2, 1:4 etc.
➢ Power: amount of acoustic energy per unit time
(watts)
➢ Intensity: power per unit area of the ultrasound
head (watts/cm2). Space average intensity and
time averaged/space average intensity(pulsed).
➢ Frequency: number of compression-rarefaction
cycles per unit of time, usually expressed in cycles
per second (Hertz)
➢ Effective radiating area (ERA): The area of
the transducer from which the US energy
radiates
➢ Duty cycle: The proportion of total treatment
the ultrasound was on
10

Depth of penetration
1
2
Majority of the ultrasound generators used in
physiotherapy are set at a frequency of 1MHZ
and/or 3MHZ.
The depth of penetration of ultrasound
beam is inversely proportional to the
frequency
1MHZ ultrasound beam has a depth of
penetration of 3-5cm and absorbed in deeper
tissues
3MHZ ultrasound beam with a depth of
penetration of 1-2cm and is absorbed in the
superficial tissues
11

Treatment Protocols
➢Preparation of the
Machine
➢Preparation of the
Patient
➢Set up the treatment
➢Termination of treatment
➢Documentation
12

Protocols
➢ Set-up up the Rx
✓ Secure pt.'s comfort and stability
of Rx
• part
✓ Plug dead, supply and power on
✓ Select Rx programme
✓ Apply coupling media
✓ Ensure the transducer is in
contact with the coupling
media on the skin
✓ Start now
✓ Keeping asking how the pt.'s
feels
➢ Preparation of the
machine
✓ Position
✓ Inspect
✓ Be assured of
functionality
✓ Bring all accessories
closer:
• Aquasonic gel
• Cotton wool
• Methylated spirit
• Water in a bowl
➢ Preparation of the
patient
✓ Inform your patient
✓ Remove metals
✓ Expose the Rx part
✓ Remove hair if necessary
✓ Wash or swab
✓ Inspect the Rx part
✓ Check for intact
sensation
✓ Demand co-operation
13

Protocols
➢ Termination
✓ Return intensity to
zero
✓ Remove transducer
✓ Cut the mains supply
✓ Clean the skin and
the transducer
✓ Inspect
➢ Documentation
✓ Date
✓ Machine
✓ Intensity
✓ Frequency
✓ Mode
✓ duration
✓ Coupulant
✓ Region
✓ Response of Rx`
14©2020 Rohit Bhaskar

Application
Principles
➢ Rx surface parallel to the skin
➢ Even pressure maintained to
exclude air and balance
irregularities in sonic field
➢ Transducer moved
continuously over the skin
surface
➢ Rate of movement must be slow
enough to allow tissue to
deform and fast enough to
avoid hot spots
➢ Pattern of movement- series
of overlapping parallel
strokes, circles or figure 8
Techniques of Application
1. Direct contact
2. Water bath: degased water of
comfortable temperature,
transducer held 1cm parallel
to the skin inside the water
keeping
3. Water bag
15

Dosage
➢ Factors to consider
✓ Receny of injury
✓ Depth of tissue
✓ Nature of the lesion
✓ Size of the area
✓ Attenuation
✓ Area of transducer
➢ Acute conditions
✓ Intensity: 0.25 or
0.5 watts/cm2
✓ Time: 2-3minutes
✓ Failure to improve progress
to 0.8watts/cm2 or increase
time to 4 0r 5minutes
➢ Chronic conditions
✓ Start dose: 0.8watts/cm2for
4minutes
✓ Failure to improve progress
to 1watts/cm2 for
4minutes, 1watts /cm2 for
6minutes, to 1.5watts/cm2
for 6minutes, 1.5watts/cm2
for 8minutes, 2watts/cm2
for 8minutes
✓ Note: A dose of
2watts/cm2 for 8minutes
is maximum permitted
16

Physiological effects
➢Chemical Reactions
➢Biological Responses
➢Mechanical
Responses
➢Thermal Effects
17

➢ Biological responses
✓ Increase membrane
permeability which
enhances transfer of fluid
and nutrients to tissues
✓ Acoustic Streaming: is
unidirectional flow of tissue
components which occurs
particularly at the cell
membrane. Streaming
produce changes in the rate
of protein synthesis and
could thus have a role in the
stimulation of repair.
➢ Chemical reaction
Ultrasound vibration
stimulate tissue to enhance
chemical reactions and
processes and ensure
circulation of necessary
elements and radicals for
recombination.
18

➢ Mechanical responses
✓ micro massage: cells are
alternately compressed
and then pulled further
apart. This increase
mobility of intracellular
fluids and thus helps to
reduce oedema.
✓ Tendon extensibility:
ultrasound apparently
increases the
extensibility of
tendons, muscles and
scar tissues.
➢ Thermal effects: as
ultrasonic waves
are absorbed they
are converted to
thermal energy
(heat)
19

Clinical application of US
➢ Soft tissue injuries
➢ Oedema
➢ Varicose ulcers
➢ Pain control
➢ Chronic rheumatoid and arthritic
conitions
➢ Tendon injuries
➢ Resorption of calcium deposits
➢ Bone fractures
➢ Carpal tunnel syndrome
➢ phonophoresis
20

Contraindications
➢Vascular
conditions
➢Radiotherapy
➢Tumours
➢Pregnancy
➢Cardiac disease
➢Implant
➢Anaesthetic area
➢Acute sepsis
21

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