Electro Magnetic Spectrum

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    The electromagnetic spectrum is the range ofall possible frequencies of electromagneticradiation

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    http://en.wikipedia.org/wiki/Spectrumhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Spectrum
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    Electromagnetic radiation is composed ofelectrical and magnetic fields that vary overtime and are perpendicular to each other

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    Electromagnetic radiation is categorizedaccording to its frequency and wavelength,which are inversely proportional to eachother

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    It includes Extremely low frequency (ELF) waves, Shortwaves, Microwaves Infrared (lR) radiation, Visible light, and Ultraviolet A and B X-rays and Gamma rays

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    Definition Diathermy is the application of high frequency

    electromagnetic energy that is primarily used togenerate heat in body tissues.

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    Frequency and Wavelength Within the radiofrequency range 3 kHz to 300 Mhz Wavelengths of 1 m to 100 kmFor therapeutic purpose The 27.12 MHz band is used for SWD device

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    Types of Shortwave Diathermy

    Capacitive FieldInduction Field

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    Capacitive Field DiathermyUses the patients tissues as a part of the circuit

    The tissues electrical resistance produces heatSelectively heats skinMuscle is heated via conduction from theadiposeAlso referred to as condenser field diathermy

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    Create Stronger Electrical

    Field Than Magnetic Field

    Electrical Field Is The Lines of

    Force Exerted on ChargedIons That Cause Movement

    From One Pole To Another

    Center Has Higher Current

    Density Than Periphery

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    Patient Is Between Electrodes and BecomesPart of CircuitTissue Is Between Electrodes in a Series CircuitArrangementThe Tissue That Offers The GreatestResistance To Current Flow Develops The Most

    Heat Fat Tissue Resists Current Flow Thus Fat Is Heated In An Electrical FieldPrecaution:

    electrical field may overheat area with large fatcontent

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    Capacitor Electrodes Air space plates

    Pad electrodes

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    Air Space PlatesAir space plates are an example of acapacitor electrodeConsists of two metal plates with a diameterof 7.5 17.5 cm surrounded by a glass orplastic plate guardThe metal plates may be adjustedapproximately 3 cm within the plate guard,thus changing the distance from the skin

    The area to be treated is placed between theelectrodes and becomes part of the externalcircuit

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    The sensation of heat tends to be in directproportion to the distance of the plate from

    the skinCloser the plate is to the skin, the better theenergy transmissionLess reflection of the energy

    SPACINGThe closer plate generate more surface heatin the skin and the subcutaneous fat in thatareaParts of the body that are low insubcutaneous fat content (e.g., Hands, feet,wrists, and ankles)

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    Pad ElectrodesTrue capacitor electrodes ,Must have uniform contact pressure on thebody partThe patient is part of the external circuit

    Several layers of towelling are necessary tomake sure that there is sufficient spacebetween the skin and the padsThe pads should be separated so they are at

    least as far apart as the cross-sectionaldiameter of the pad

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    Closer the spacing of the pads, the higher thecurrent density in the superficial tissuesIncreasing the space between the pads willincrease the depth of penetration in the tissuesThe part of the body to be treated should becentred between the pads

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    SIZE OF ELECTRODESElectrodes should be larger

    than the structure beingtreatedStructure to be treated liesin more even central partof the field

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    If treatment area b/w the electrodes is smallerthan the electrodes, the line of force bend intowards the limb

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    If the diameter of the electrodes is smallerthan that of limb, the line of force spread in

    tissuesCauses more heat in superficial tissues

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    POSITION OF ELECTRODESAimed at directing the electric field through

    the structure to be treatedIf the structure is of high impedance, positionthe electrodes as far as possibleElectrodes should be placed parallel to theskin, otherwise the field concentrates on areacloser to the electrode

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    Both electrodes should be of same sizeDifferent sizes forms capacitor with different

    platesRequires different quantities of electricity forchargingPuts an uneven load on machine anddifficulties in tuning

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    TYPES OF POSITIONINGCONTRAPLANARCOPLANARCROSS-FIREMONOPOLAR

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    CONTRAPLANAR POSITIONING OF ELECTRODESSuitable for the treatment of deeply placed

    structuresElectrodes are placed over opposite aspects ofthe limb

    COPLANAR POSITIONING OF ELECTRODESElectrodes placed side by side on same aspectDistance between electrodes is more than thetotal width of spacing

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    Heating is more superficial than with coplanarmethod

    CROSS FIRE TREATMENTHalf the treatment is given with the electrodes inone position, then the arrangement is changed sothat the electric field lies at right angles to theobtained during first part of the treatment.Mainly used to treat the walls of cavities containingair e.g. SINUSES

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    The line of force pass through the tissues betweenthe electrodes but avoid the cavityThus the walls of cavity which face the electrodesare not treated

    The position of electrodes are changed so that thefield lies at right angles to previous one

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    Longitudinal- plates are placed at each end ofthe limb

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    MONOPOLAR TECHNIQUEThe active electrode is placed over the site of lesionand the indifferent electrode is applied to distant ormay not be usedSeparate electric field is set up under each electrodeHeating is superficial

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    INDUCTION FIELD DIATHERMYPlaces the patient in the electromagnetic

    fieldSelectively heats muscle

    Also referred to as:

    Magnetic field diathermy

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    A coil is housed within adrumCurrent flowing withinthe coil produces arotating magnetic fieldMagnetic field producessecondary current callededdy currents in thetissuesEddy currents cause

    friction that produce heatAlthough rare, cables aresometimes used in placeof drums

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    Electric currents cause charged particles inthe tissue to oscillate.

    The friction produced by this oscillationcauses an elevation in tissue temperatureInductive coils can heat both deep andsuperficial tissues, but they produce the

    Most heat in tissues closest to the applicatorand in tissues with the highest electricalconductivity.

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    Available in two basic forms, Cables and

    DrumsThe cables are bundles of plastic-coated wires thatare applied by wrapping them around the patient'slimb

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    A drum applicator is made of a flat spiral coilinside a plastic housing

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    TECHNIQUES OF SWDTesting of machine

    Preparation of patientSelection of electrodesPosition and size of electrodesConnecting leads

    Application of currentDosage

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    INDICATIONS Promoting injury and wound healing after the acute stage of the injury.

    Reducing non-inflammatory muscle pain, and muscle spasms

    Reducing Myofascial trigger point p