Shortwave and Microwave Diathermy

Shortwave and Microwave Diathermy part(2)

Induction Electrodes(Drum Electrode)

• One Or More Monopolar Coils Rigidly Fixed In A Housing Unit

• May Use More Than One Drum Depending On Area Treated

• Penetration– Deeper Soft Tissues

• Toweling Important2

Heating With Continuous SWD• Patient Sensation Provides Basis For Recommendations

Of Continuous SWD

• Dose I (Lowest) (<38 W) - No Sensation of Heat • Dose II (Low) (~80 W)- Mild Heating Sensation • Dose III (Medium) (80-300 W) - Moderate or Pleasant

Heating Sensation • Dose IV (Heavy) (>300 W) -Vigorous Heating Within Pain

Threshold

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Pulsed SWD

• Referred To By Different Names– Pulsed Electromagnetic Energy (PEME)– Pulsed Electromagnetic Field (PEMF)– Pulsed Electromagnetic Energy Treatment

(PEMET)

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Pulsed SWD

PSWD Mean Power Calculations

• Pulse Period (Pulse on + off time) = – Peak Pulse Power (W) / Pulse Rep Freq (Hz)

• Percentage On Time =– Pulse Duration (msec) / Pulse Period (msec)

• Mean Power =– Peak Pulse Power (W) / Percentage on Time

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Example

• Peak Pulse Power = 800 W• Pulse Duration = .4 ms• Pulse Frequency = 200 Hz• Pulse Period = 800 W / 200 Hz = 4 ms• % on time = .4 / 4 = .10 or 10%• Mean Power = 10% of 800 = 80 W– End Result = thermal effect– < 38 W = no heating

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Pulsed SWD

• Interrupted Output Delivered In Series Of High-Frequency Bursts (40-400 usec)

• Pulse Rate Selected With Pulse Frequency Control (1–1000 Hz)

• Off-Time Longer Than On-Time• Low Mean Power Output• Uses Drum Electrode

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Shortwave Diathermy vs.Ultrasound

Pulsed SWD Produces The Same Magnitude And Depth Of Muscle Heating as 1MHz Ultrasound (Draper, JAT 1997)

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Treatment Time

• Most Typically SWD Treatments Last For 20-30 Minutes

• Remember As Skin Temperature Rises Resistance Falls

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When Should Diathermy Be Used?

If The Skin Or Some Underlying Soft Tissue Is Tender And Will Not Tolerate Pressure

In Areas Where Subcutaneous Fat Is Thick And Deep Heating Is Required Induction method

When The Treatment Goal Is To Increase Tissue Temperatures Over A Large Area

If The Skin Or Some Underlying Soft Tissue Is Tender And Will Not Tolerate Pressure

In Areas Where Subcutaneous Fat Is Thick And Deep Heating Is Required Induction method

When The Treatment Goal Is To Increase Tissue Temperatures Over A Large Area

SWD Guidelines

• Indications– Continuous and Pulsed

• Precautions• Contraindications

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الكهربية بالشرارة القصيرة الموجات مولدSpark gap radio frequency generator

RFC1

RFC2SG1

C1

C2

C3

Vacuum tube sine wave circuits

Cutting and coagulation waves

بالثيراترون الكي تيار مولد Thyratron coagulation current generator

Diathermy Semiconductor Circuits

Radiofrequency power amplifier semiconductor circuit

Electrosurgical Units (ESU) and Cautery Machines

• Function• Electrosurgery is the application of a high-frequency electric

current to biological tissue as a means to cut, coagulate, desiccate, or fulgurate tissue.

• Its benefits include the ability to make precise cuts with limited blood loss in hospital operating rooms or in outpatient procedures.

• Cautery, or electrocautery, is the application of heat to tissue to achieve coagulation. Although both methods are sometimes referred to as surgical diathermy .

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How it works• In electrosurgical procedures, the tissue is heated by an alternating electric current

being passed through it from a probe. • Electrocautery uses heat conduction from an electrically heated probe, much like a

soldering iron. • Electrosurgery is performed using an electrosurgical generator (also referred to as

power supply or waveform generator) and a hand piece including one or several electrodes, sometimes referred to as an RF Knife , or informally by surgeons as a "Bovie knife" after the inventor.

• Bipolar electrosurgery has the outward and return current passing through the handpiece, whereas monopolar electrosurgery returns the current through a plate normally under the patient.

• Electrosurgery is commonly used in dermatological, gynecological, cardiac, plastic, ocular, spine, ENT, orthopedic, urological, neuro- and general surgical procedures as well as certain dental procedures.

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Microwave Diathermy• Two FCC Assigned Frequencies-2456 MHz and 915 MHz• MWD Has Higher Frequency and Shorter Wavelength

Than SWD• Generates Strong Electrical Field and Relatively Little

Magnetic Field• Advantage: better focus wave on body, thereby more

local heating affects • Disadvantage: Depth Of Penetration Is Minimal In Areas

With Subcutaneous Fat > 1 cm

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Microwave Diathermy Unit

• A= Power Switch• B=Timer• C=Output Meter (indicates relative output in watts• D= Power Output Level Knob• E= Amber Light-Warming up / Red Light- Ready

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MWD Applicators (Electrodes)

• Circular Shaped Applicators – 4” or 6”– Maximum Temperature At Periphery

• Rectangular Shaped Applicators– 4.5 x 5” or 5 x 21”– Maximum Temperature At Center

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Microwave Applicator Set-Up

• Microwave Applicator Beams Energy To Patient

• Must Pay Attention To Cosine Law• In 915 MHz Units Applicators Placed 1 cm

From Skin• 2456 MHz Units Have Manufacturer

Recommended Distances and Power Outputs (Uses Antenna)

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Best Treated areas for Microwave

• Tendons of foot, hand and wrist• AC and SC joints• Patellar tendon• Distal tendons of hamstrings• Achilles tendon• Other areas of low subcutaneous fat

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