Microwave Diathermy

Microwave Diathermy Mohammed Taher AhmedPh.D PT,Rehabilitation Health ScienceCollege of Applied Medical Science

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

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)

Microwave Diathermy • Microwave Diathermy (MWD) is a high frequency electromagnetic radiation lies between infrared and shortwave. Their frequency ranges between 300-3000MHz, with corresponding wavelengths of 1m-10mm.

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

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 usedto direct the waves onto the tissues.

Emitter = Applicators Applicator must be very flat to avoid reflection of energy .

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

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 greaterdepth (half value thickness=3.5cm). • Tissue with high water content (muscle, blood) are penetrated to superficial depth (=0.7cm).

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 Metalshould 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.

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

INDICATIONS • Soft tissue injury • Mobilization • Pain relief

Contradictions of MWD 13 • 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.

Dangerous of MWD 14 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

Microwave Diathermy Advantages • 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

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: 20 -30minutes Frequency of Treatment;daily or alternating days depending on • Response to treatment • Patients condition/availability

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

Self test questions • Compare and contrast between SWD and MWD

Microwave Diathermy