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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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