Microwave diathermy

Microwave diathermy Objectives discuss the working of the generator Identify indications and contraindications describe procedure of treatment and techniques of application of micro wave diathermy identify Advantages, disadvantages and danger

Microwave diathermy Electromagnetic radiation which lies between the shortwave and the infrared regions of the electromagnetic spectrum. Frequency of microwave is 300 – 30000 MHz The wavelength is 10mm – 1m. Frequency and wavelength used for therapeutic purposes 2450 MHz is the frequency that is widely available for therapeutic purposes. Effective penetration of it is about 30mm But the lower frequencies have the ability to penetrate more. Frequency Wavelength 2450 12.2 915 32.8 434 69.1

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

Circuit

Microwave diathermy: Production High frequency current is fed to a device called magnetron. Magnetron is a special type of thermionic valve characterized by centrally placed cathode, which is surrounded by a circular metal anode. Primary function of the magnetron is to generate oscillating currents directly from high velocity electron motion.

Microwave diathermy: Production These currents are passed to the antenna that emits microwaves. The antenna is a piece of wire that is mounted in front of a metal reflector which emits the waves in one direction. Output of the microwave energy can be controlled by varying the power supply to the magnetron. The frequency produced depends on the structure of the magnetron and it is therefore fixed.

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

Microwave diathermy: Physiological effects Heat production in the tissues is the prominent effect. Water containing tissues such as muscles absorb more rays than the tissues like fat and bone. Skin is heated up to a greater extend than the other tissues. However, 50% of rays are reflected from the air-skin surface.

Microwave diathermy: Therapeutic uses Pain Muscle spasm Chronic inflammation Delayed healing Chronic infection Fibrosis

Microwave diathermy: Indications Disorders of musculoskeletal conditions Sprains Strains Capsular lesions Degenerative joint disease Chronic rheumatoid arthritis Stiffness in superficial joints Haematoma

Microwave diathermy: Indications Superficial inflammatory or infective conditions Tenosynovitis Bursitis Synovitis Infected surgical incisions Carbuncles Abscesses

Contraindications Over malignant tissues Over ischemic tissues Moderate and excessive oedema Over wet dressings and adhesive tapes Metallic implants Pace makers Over growing bone Haemorrhagic areas Tuberculous joints Impaired thermal sensation Unreliable patients The eyes Recent radiotherapy Hypersensityvity to heat Acute infection or inflammation Obesity Analgesic therapy Venous thrombosis or phlebitis Pregnancy Menstruation Acute dermatological conditions Severe cardiac conditions Blood pressure abnormalities

Dosage Duration: 20 minutes is the most favorable treatment time. Intensity: Only safe measure is the sensation of warmth described by the patient. Frequency of treatment: treatment may be given daily or on alternative days. It is most beneficial if given once or twice daily.

Techniques Variation in the application depends on the size and the heating pattern of the emitter 9 director/ transducer/applicator/radiator).

Microwave diathermy: Application The patient should be positioned in well comfortable manner with adequately exposing the part to be treated. Explain the procedure to the patient. Check for contraindications. Localize the site to be treated. Test the skin for hot and cold sensation. Pair of microwave goggles should be given to the patient. Select the type of director and fix it to the machine. Check all the connections.

Microwave diathermy: Application Emitter should be position to get a beam of radiation which strikes the skin at right angles. Emitter- skin distance is about 2 cm. Test the machine by placing the therapists hand under the director. Switch on the machine after setting the timer Instruct the patient to not to look at the applicator and warn him regarding the burns.

Advantages and disadvantages Simplicity of application and operation of machine Accurate localization of heat. Low frequency microwaves causes selective heating in muscles. Deep structure cannot be heated. It can heat only one aspect of a joint. Skin burns may develop rapidly.

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