Microwave Diathermy (PowerPoint)

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					Microwave Diathermy
Properties of Microwave Diathermy
   Microwave diathermy (MWD), is a form
    of electromagnetic radiations (part of
    electromagnetic spectrum), lying between
    shortwave and infrared waves. The
    microwaves diathermy gives superficial
    heating where energy is first absorbed at
    the surface of the body (skin) and a part
    of it penetrate and absorbed in deep
    tissues.
Properties of Microwave Diathermy
   The general frequency of microwave is
    between 300 to 30000MHz with wave length
    of 10mm to 1 meter.
   The therapeutic microwave generators used
    frequency of 2450MHz with wave length of
    122.5mm.
   Physiotherapeutic microwaves at 327mm
    (915 MHz) and 690mm (433.9MHz) may be
    also available to give minimal heating of
    subcutaneous tissues and produce more
    heating of underlying tissues.
Production of Microwave Radiation
 The generator used to produce
  microwaves has three main components:
 A multi-cavity magnetron valve.
 A coaxial cable to transmit the high
  frequency energy to an antenna.
 A director for transmitting the energy
  (through air) to the patient.
Production of Microwave Radiation
   The magnetron (a diod valve) produces a high
    frequency alternating current which is carried
    by coaxial cable to the transducer (director).
    The coaxial cable transmit the energy to the
    director where a radiating system comprising an
    antenna within a reflector is used to direct the
    microwave to the patient.
    Directors Used in Microwave
            Applications
 There are different shapes of directors
  used in microwave applications:
 Large circular field director: the effective
  diameter is 200mm. The heating pattern is
  more intense around the outer portion
  than the centre. The power output range
  is up to 250 watts.
     Directors Used in Microwave
             Applications
   Small circular field director: the effective
    diameter is 100 mm. the heating pattern is
    more intense around the outer portion
    than in the center. The power output is up
    to 25 watts
     Directors Used in Microwave
             Applications
   Longitudinal director: the effective
    treatment area is 500mm by 100mm. the
    heating pattern tends to be more
    concentrated in the center of this area.
    The power output is up to 250 watts
Biophysical and Biochemical Effects
             of MWD
 Penetration: the depth of penetration
  depends on the frequency of the wave
  and the medium. The effective penetration
  of 2450MHz is approximately 30mm.
 Absorption: non-polar molecules will
  distort toward the alternating charge in
  the field.
 -Dipolar molecules will rotate back and
  for the ions will vibrate in the field
  direction        heat energy.
Biophysical and Biochemical Effects
             of MWD
 Reflection: the proportion of waves reaching the
  deeper tissues is also dependent upon the
  amount of energy which is reflected at the air-
  skin, skin-fat, and the fat-muscle. At frequencies
  below 1000MHz most of the distribution of the
  energy depends critically on the thickness of the
  skin and the subcutaneous fat.
 Heat conduction: heat applied to the skin (in a
  restricted area) results in an increased blood flow
  of the skin accompanied by vasodilatation. Mild
  heat produces reflex reduction of increased
  muscle tone.
        Therapeutic Effects of
        Microwave Diathermy
   Relief of pain: by microwave diathermy is
    useful in the treatment of traumatic and
    rheumatic conditions affecting superficial
    muscles, ligaments and small superficial
    joints.
   Reduce muscle spasm: may be reduced
    directly by microwave diathermy or may be
    reduced by relieving of pain.
   Inflammation: increase in the blood supply
    will increase venous return from the
    inflamed area and aids the reabsorption of
    edema exudates.
      Therapeutic Effects of
      Microwave Diathermy
 Delayed healing: to promote healing of
  open skin by increase cutaneous
  circulation.
 Infection: MWD can control the chronic
  infection by increasing the circulation.
 Fibrosis: heat increase the extensibility of
  fibrous tissues such as tendons, joint
  capsules and scars.
          Dosage of MWD

 Duration of treatment 20 minutes is the
  optimum.
 :Intensity: the patient should feel mild
  and comfortable warmth.
 Frequency: daily or on alternating day.
        Indications of MWD
 Musculoskeletal disorders:
 Sprain- strain – muscle and tendon tear –
  degenerative joint disease- joint stiffness
  in superficial joints- capsular lesions.
 Superficial inflammatory or infective
  conditions :
 Tenosynovitis – bursitis – synovitis –
  infected surgical incisions – carabuncles –
  abscess.
              Contra-indications
   Over malignant tissues.
   Over ischemic tissues.
   Moderate and excessive edema.
   Over wet dressings and adhesive tapes.
   Metal implants.
   Pacemaker.
   Over growing bone.
   Male gonads: repeated irradiation can cause sterility.
   Hemorrhage.
   Tuberclous joints.
   Impaired thermal sensation.
   Unreliable patients.
               Contra-indications
   The eyes: cause cataract.
   Recent radiotherapy.
   Hypersensitivity to heat.
   Acute infection or inflammation.
   Obesity: with 2450MHz microwave, there is danger of
    producing an excessive heat in the subcutaneous fat layer.
   Analgesic therapy: the thermal sensation diminished.
   Venous thrombosis or phlebitis.
   Pregnancy: heat applied to pelvis or hip in pregnancy may
    cause hemorrhage or miscarriage.
   Menstruation.
   Acute dermatological conditions.
   Severe cardiac conditions.
   Blood pressure abnormalities.