1. Microwave Diathermy
Mohammed Taher Ahmed Ph.D PT, Rehabilitation Health Science College of Applied Medical Science

2. Outline Define microwave current Review the physics of the current
Effects of application
Indications, Contra-indications
Procedure of application 2

3. What dose Diathermy Means ?
Diathermy is a Greek word “ through heating”, in which a high frequency (>10.000Hz) electromagnetic current applied to induce deep heating within body tissue, to induce physiological effects for therapeutic purpose.
Shortwave Diathermy (SWD)
Microwave Diathermy(MWD)
Pulsed Electromagnetic (PEM)

4. Microwave Diathermy
Microwave Diathermy (MWD) is a high frequency electromagnetic radiation lies between infrared and shortwave. Their frequency ranges between MHz, with corresponding wavelengths of 1m-10mm.
Frequency MHz
Wavelength Cm
2450
12.33
915
32.7
433.9 69

5. Microwave Diathermy Generator
Power supply
Magnetron
Timing circuit
Applicators (emitter, a director)

6. Magnetron
The high frequencies of micro-thermy are obtained from the magnetron, which is perforated with tiny holes, through which the electrons flow into the treatment heads.
The special design of the treatment heads shapes focuses the field directly at the target area.
The whole device is used to direct the waves onto the tissues.

7. Emitter = Applicators
Applicator must be very flat to avoid reflection of energy .
Circular shape
Rectangular shaped
Diameter
4-6inches
4.5X5/ 5X21 inches
Temperature
Maximum at periphery of each radiation area
Maximum at central of radiation area

8. Principle Related To Use Of MWD
Deep heating modality
Emits strong electrical field/ little magnetic field.
Depth of penetration is frequency dependent.
Produces much more localized & concentrated heating effect than SWD.
Providing a more shallow tissue heating effect, depends on the type of tissue involved.
Reflection Refraction Absorption,

9. Principle Related To Use Of MWD
The effective depth of MWD penetration (half-value depth) is about 4.5 cm, so the depth of heating is intermediate between that of infrared radiation (2cm) and short wave diathermy (>5cm).
MWD are strongly absorbed by tissues with high fluid content are heated most, while penetrated by tissues with low fluid content (e.g. fat or bones).
Tissues with low water content (fat) are penetrated to a greater depth (half value thickness=3.5cm).
Tissue with high water content (muscle, blood) are penetrated to superficial depth (=0.7cm).

10. Principle Related to Use of MWD
The patients does not form apart of the circuit in MWD, so no tuning is necessary as in SWD.
Transmits as free space radiation, so needs only one emitter (applicator).
No Metal should be within 4 feet of MWD, since it will interfere with the signal.
Spacing is required between the skin and the applicators with MWD, where the applicator on a short wave unit my be placed in contact with treatment area.

11. Physiological and Therapeutic Effects of MWD
When the electromagnetic radiation of MWD enters the body causes
Ionic movement (vibration).
Rotation of dipoled.
Distortion of non-polar molecule
Physiological effects
Therapeutic effects
Effects on metabolism
Effects on blood supply
Effects on nervous tissue
Effects on muscular tissue
Effects on sweat glands
Relief of pain and muscle spasm Promote healing
Infection
Increase the extensibility

12. INDICATIONS
Soft tissue injury
Mobilization
Pain relief

13. Contradictions of MWD
Eyes: Irradiation to the eyes may develop opacities/ cataract.
Malignancy: should not be applied to regions of malignant growth or tuberculosis.
Cardiac pacemakers.
Genital area (sterility).
Pregnancy (miscarriage , hemorrhage)
Unreliable patients,
Metallic implants,
Hypersensitivity to heat,
Impaired sensation
Circulatory defects: Such as hemorrhage, thrombosis, phlebitis and other vascular lesions. 13

14. Dangerous of MWD Burn Poor techniques
Inability of tissue to dissipate heat (circulatory defect)
Inability to detect heat (impaired sensation)
Implanted metal
Moist skin
Treatment near the eye
Pregnancy (miscarriage , hemorrhage)
Damage to the eye
Damage to the equipment 14

15. Microwave Diathermy Advantages Disadvantages
Operation of the machine is simple
Comfortable for the patient
Localized heat to small surfaces
No overheating if precautions are followed
Disadvantages
Not for deep structures
Heats only one aspect of the joint
Risk of burn

16. Treatment Parameter of MWD
The MWD requires warm-up period of 4 minutes, to allowed the magnetron to develop enough energy
Spacing of Applicators
For small treatment area is 2-6cm
For large treatment area is 10-15cm
Intensity of Treatment
Sensation of warmth
Feel no more than a mild comfortable warmth.
Trim of Treatment: minutes
Frequency of Treatment; daily or alternating days depending on
Response to treatment
Patients condition/availability

17. General Guideline & Safety When Using Diathermy
Question patients (contraindications and previous treatment).
Position patient ( comfort, support, relaxed).
Inspect part to be treated (check for skin rashes, infection, or open wound).
If indicated, drape area with toweling.
Place electrodes on treated area then switch on the machine.
Set pulse duration, pulse frequency, treatment time, and adjust intensity.
Periodically ask patient if heating is too vigorous.
When timer shuts off, terminating the treatment and turn all dials to zero.
Assess treatment efficiency ( inspect area, feedback from patients ).
Record treatment parameters

18. Self test questions Compare and contrast between SWD and MWD MWD SWD
Frequency &wavelength
Therapeutic frequency and wavelength
Circuit used
Field used
Factors affecting heat penetration/ absorption
Depth of penetration
Treatment time /intensity
Advantages