microwave diathermy
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Sreeraj S R
Electromagnetic spectrum
1 101 102 103 104 105 106 107 108 109 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022
Radio & TVInfra Red
Microwaves
Gamma-Rays
X-Rays
Ultra Violet
Non-ionising Radiation(generally not so bad)
Ionising Radiation
(generally bad)
Frequency (Hertz)Sreeraj S R
Definition Irradiation of tissues with radiation in the shorter wireless part of the
spectrum (Hertzian rays) i.e. the wave length is between infra red and short wave diathermy.
The general frequency of microwave is between 300 to 30000MHz with wave length of 1 m to 1 mm.
Frequently used frequency and wavelength are,
Frequency Wavelength 2450 MHz 12.25 cm 915 MHz 32.7 cm 433.92 MHz 69 cm
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Fan and cathodeHeater control
circuits
Powersupplyfrom
mains
Magnetron
Mains
Intensity control
Reflector
Emitter
Antenna
Coaxial cable
Production
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Magnetron
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Microwave Diathermy Unit
A= Power Switch B=Timer C=Output Meter (indicates output in watts) D= Power Output Level Knob E= Amber Light-Warming up / Red Light- Ready
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Applicators
Circular Shaped Applicators Maximum Temperature At Periphery
Rectangular Shaped Applicators Maximum Temperature At Center
Contact applicatorsSreeraj S R
Physical behaviour
Absorption, Grotthus Law Transmission Reflection Refraction
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Physiological effects
Consequence of tissue heating due to
o Ionic movemento Dipole rotationo Molecular distortion Strongly absorbed by tissues of high
water content
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Therapeutic Effects
Relief of pain
Reduce muscle spasm
Promote healing
Infection
Increase the extensibility
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Dosage
20 min for vascular adjustment If significant heating required 30 min
would be reasonable Intensity: the patient should feel mild
and comfortable warmth. Frequency: daily or on alternating
day.
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Principles of Application
Preparation of patient
Preparation of apparatus
Preparation of part to be treated
Setting up- Emitter should be positioned so that radiations strike the
surface at right angles
Instruction and warning
Application
Termination
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Contra-indications
Over malignant tissues. Over ischemic tissues Over wet dressings and
adhesive tapes. Metal implants. Pacemaker. Over growing bone. Male gonads: repeated
irradiation can cause sterility.
Hemorrhage. Tuberculous joints. Impaired thermal
sensation. Unreliable patients.
The eyes: cause cataract. Recent radiotherapy. Hypersensitivity to heat Acute infection or
inflammation. 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.
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