2022 Deep Thermal_Lecture

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Treatment Plan
• Ultrasound should be applied to the right wrist over the area of greatest
soft tissue shortening and the joint can be placed in a stretched position
while the ultrasound is being applied.
▪ A frequency of 1 MHz or 3 MHz could be used depending on the
diameter of the patient’s wrist.
• The treatment parameters should consist of continuous duty cycle to
increase the tissue extensibility with an intensity of 1.0 to 1.5 W/cm2.
• Adjustments of the output may be necessary so the patient may feel a
sensation of mild warmth after 2 to 3 minutes.
• A small sound head of 5 centimeters is sufficient to cover the treatment
area for approximately 5-7 minutes.
• The shortened soft tissue should then be placed in a stretched position
immediately following the ultrasound application.
▪ Treatment should be applied 3 times per week and continued as long
as progress is being made and the patient is achieving the outlined
therapeutic goals.

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TYPES OF DIATHERMY

Microwave Diathermy(MWD)
Shortwave Diathermy (SWD)

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MICROWAVE DIATHERMY

• Microwave Diathermy (MWD) is a high
frequency electromagnetic radiation lies
between infrared and shortwave. Their
frequency ranges between 300-3000MHz,
with corresponding wavelengths of 1m-
10mm.

Frequency MHz Wavelength Cm
2450 12.33
915 32.7
433.9 69

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Principle Related To Use Of MWD

• DEEP HEATING MODALITY
• Emits strong electrical field/ little magnetic field.
• Depth of penetration is frequency dependent.
• Produces much more localized & concentrated

heating effect than SWD.
• Providing a shallower tissue heating effect,

depends on the type of tissue involved.
• Reflection Refraction Absorption

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Principle Related To Use Of MWD

The effective depth of MWD penetration (half-
value depth) is about 4.5 cm, so the depth of
heating is intermediate between that of
infrared radiation (2cm) and short-wave
diathermy (>5cm).

MWD are strongly absorbed by tissues with
high fluid content are heated most, while
penetrated by tissues with low fluid content
(e.g. fat or bones).

• Tissues with low water content (fat) are
penetrated to a greater depth (half value
thickness=3.5cm).

• Tissue with high water content (muscle,
blood) are penetrated to superficial depth
(=0.7cm).

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Principle Related to Use of MWD

◼ The patient does not form a part of the
circuit in MWD, so no tuning is
necessary as in SWD.

◼ Transmits as free space radiation, so
needs only one emitter (applicator).

◼ No Metal should be within 4 feet of
MWD, since it will interfere with the
signal.

◼ Spacing is required between the skin and
the applicators with MWD, where the
applicator on a short-wave unit my be
placed in contact with treatment area.

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Physiological and Therapeutic Effects of

MWD

Physiological effects Therapeutic effects

• Effects on metabolism • Relief of pain and

• Effects on blood supply muscle spasm Promote

• Effects on nervous healing

tissue • Infection

• Effects on muscular • Increase the

tissue extensibility

• Effects on sweat glands

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Microwave Diathermy

Advantages Disadvantages

• Operation of the • Not for deep
machine is simple structures

• Comfortable for the • Heats only one
patient aspect of the
joint
• Localized heat to small
surfaces • Risk of burn

• No overheating if
precautions are
followed

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Treatment Parameter of MWD

The MWD requires warm-up period of 4
minutes, to allowed the magnetron to
develop enough energy
Spacing of Applicators

◼ For small treatment area is 2-6cm
◼ For large treatment area is 10-15cm

Intensity of Treatment

◼ Sensation of warmth
◼ Feel no more than a mild comfortable

warmth.

Time of Treatment: 20 -30minutes
Frequency of Treatment; daily or alternating

days depending on
◼ Response to treatment
◼ Patients condition/availability

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DIRECTORS USED IN MICROWAVE
APPLIC ATIONS

• Circular Directors

• The heating pattern is
more intense around
the outer portion than
the center

• Rectangular Directors

• The heating pattern
tends to be more
concentrated in the
center of the treated
area

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SHORTWAVE
DIATHERMY

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SHORT WAVE DIATHERMY

▪ SWD is a modality that produces
deep heating via conversion of
electromagnetic energy to thermal
energy.

• The pattern of heat produced depend
on:

• Frequency used.

• Type of SWD unit.

• Water content of the tissues.

• The commonly used Shortwave
diathermy current freq. in therapy is
27.12 MHz with wavelength of 11
meters

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Diathermy Modalities:

either continuous or pulsed (PSWD).

PSWD: application of series of short
pulses of SWD so that short periods of
SWD interrupted by gaps where there is
no SWD.

• The pt. receives lower dose of SWD
energy if compared with continuous
SWD applied of the same time. The
tissues will receive lower thermal load.

SWD: produce both deep and superficial
tissue heating, under certain controlled
conditions

• it’s applied for 20 min at the
maximum tolerable dose

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TYPES OF SHORTWAVE DIATHERMY

•Induction Field
•Capacitive Field

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INDUCTION FIELD DIATHERMY

• Places the patient in the electro-
magnetic field

• Current flowing within the coil
produces a rotating magnetic field

• Magnetic field produces eddy currents
in the tissues

• Eddy currents cause friction that
produce heat

• Selectively heats muscle

• Also referred to as: – Magnetic field
diathermy

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CAPACITIVE FIELD
DIATHERMY

• Uses the patient’s tissues as a part of the
circuit

• The tissues electrical resistance produces heat

• Selectively heats skin

• Muscle is heated via conduction from the
adipose

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THE MONODE

Two different inductive electrodes are
available:

• Monode (Drum) Electrode for
treatment of mid-sized areas.

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DIPLODE

• Diplode for treatment of large
areas and for treatment of suitable
body parts that can be warmed
from three sides at the same time.

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DIATHERMY PROVIDES
RELIEF IN:

 ARTHRITIS
 BACK PAIN
 MUSCLE SPASMS
 NEURALGIA
 MYOSITIS
 SPRAINS AND

STRAINS
 TENDONITIS
 BONE INJURIES
 BURSITIS

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UNWANTED EFFECTS OF DIATHERMY

➢The electromagnetic energy used in
diathermy can cause extreme heat in metal
devices such as bone pins, dental fillings, and
metal sutures causing burns

➢ During diathermy treatment, the patient
becomes a part of the electrical field.
Touching a bare metal object, such as a
cabinet, during diathermy can cause a shock
or burn.

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RISKS ASSOCIATED WITH DIATHERMY

Diathermy should be avoided in following cases:
✓ implanted metal devices
✓ peripheral vascular disease
✓ tissue with restricted blood supply (ischemia)
✓ cancer
✓ bleeding disorders , wound dressings
✓ severe heart, liver, or kidney conditions
✓ pregnancy

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Summary Slide