INTRODUCTION,WAVELENGTH,PARAMETERS,PRODUCTION,EFFECTS,INDICATION,CONTAINDICATION

1. MICROWAVE DIATHERMY
Dr. Paras Bhura PT
MPT (Musculoskeletal-Ortho.),MIAP, CMT, DNHE, YTTC.

2. INTRODUCTION
 Microwave Diathermy(MWD) is irradiation of tissue
with radiation in shorter wireless part of
electromagnetic spectrum.
 Its wavelength between infra-red rays and short
wave diathermic waves (hertzian rays).
 hertzian rays: An electromagnetic wave with a
frequency : 3 × 1010 hertz to1.5 ×105 hertz
 Also k/a Decimeter waves, as their wavelength lies
between 1-100cm.

3. PARAMETERS
 Frequency ranges from 300 MHz to 300 GHz.
 Wavelength ranges from 1 mm to 1 m.
 The commonly used for treatment
 Frequency : 2450 MHz, Wave length – 12.25 cm
 Frequency : 915 MHz, Wave length –32.8 cm
 Frequency : 434 MHz, Wave length – 69.1 cm

4. DIAGRAM MWD

5. PRODUCTION OF WAVES
 Its is not possible to produce microwaves by
mechanical means.
 Hence microwaves are obtained from a unique
special type of thermionic valve called the
Magnetron,
 which is perforated with tiny holes, through which
the electrons flow into the treatment heads.
 Magnetron is thermionic valve characterized by
centrally placed cathode and a surrounding circular
metal anode.

7. PRODUCTION CONT…
 Coaxial cable carries these high frequency currents
from magnetron and passes it to the antenna of
emitter.
 The applicators consist of an antenna element
backed by a reflector and endorsed within a plastic
case, one face of which is transparent to microwave
energy.
 The special design of the treatment heads shapes
and focuses the field directly at the target area.
 In this kind of treatment, the patient does not form a
part of the circuit, so no tuning is necessary as in
short wave application.

9. LAWS OF MICROWAVE RADIATIONS
 Microwave has a much higher frequency and a
shorter wavelength than shortwave diathermy.
 Generates Strong Electrical Field and Relatively
Little Magnetic Field
 Obey the laws of radiation, absorption, reflection,
refraction, inverse square.

10. PHYSIOLOGICAL EFFECT (P/E)
 Ionic movements
 Rotation of dipoles
 Distortion of molecules
 The amount of heating will be proportional to the
amount of absorbed radiation and the water content
of the tissue.
 Heating is More in muscle tissues and tissue with
more water and iron content and less in fat and
bone.

11. P/E CONT…
 Produces more superficial heating compared to
SWD and deeper compared to IRR.
 Heat production decreases as the depth increases.
 This could be because of microwaves are reflected
at various interfaces s/a
 skin-air,
 skin-fat,
 fat-muscle,
 muscle-bone interfaces.

12. P/E CONT… DEPTH OF PENETRATION
 Higher DOP with lower frequency
 DOP: 4.3 cm. with half value depth (HVD) 3 cm.
 For Muscle :HVD is 0.7 cm at frequency 2450
MHz.
 For fat, bone HWD is 3.5 cm at frequency of 2450
MHz.
 So, heating of the subcutaneous fat can be avoided
by MWD.

13. P/E CONT… DEPTH OF PENETRATION
 Higher Depth of penetration with lower frequency.
 So, frequency 915 MHz is more suitable for
therapeutic heating than 2450 MHz.
 As the wavelength increases penetration and
absorption increases in the deeper tissues.
 So, the wavelength of 32.8 cm (915 MHz) produces
more deeper heating than the wavelength 12.2
cm.(2450 MHz)

14. THERAPEUTIC USES:
 Inflammatory conditions:
 Increases blood supply and relieve muscle spasm
 Pulse mode can be used 72 hrs following trauma.
 Jumpers knee, tennis elbow, sprain, strain, etc.
 Traumatic conditions:
 For the remediation of early trauma.
 Resolve inflammation and pain.
 Enhance the extensibility of collagen fibers.
 Sports injuries, surgical lengthening of tight muscle.
 Arthritic conditions:
 Reduces pain, swelling, inflammation, increases
extensibility of collagen fibers.
 Pain relief :

15. INDICATIONS
 Pain and muscle spasm
 Tennis elbow, jumpers knee
 Sprain and strain
 Sports injuries
 Rheumatoid arthritis, O.A, A.S.
 Bacterial infection.

16. CONTRA INDICATIONS
 Diminished thermal sensation
 Defective arterial circulation
 Recent hemorrhage
 Metal implantation
 Cardiac pacemaker
 Malignancy,Cancer
 Tuberculosis of Bone, acute infection.
 Recent exposure to X-rays
 Pregnant uterus

17. ADVANTAGES
 Pain is relieved
 Healing of infections is faster
 Aids in relaxation

18. CONTRAST MWD/SWD
 Frequency is high
 Wave length is low
 Special valve-
magnetron
 Require emitter only
 Does not require tuning
 Lesser than MWD
 Wave length is high
 Oscillator circuit
 Require two electrodes
 Require tuning
MWD SWD