1. Microwave diathermy

2. 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

3. Microwave diathermy
Electromagnetic radiation which lies between the shortwave and the infrared regions of the electromagnetic spectrum.
Frequency of microwave is 300 – 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

4. 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

5. Circuit

6. 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.

7. 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.

8. 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

9. 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.

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

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

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

13. 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

14. 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.

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

16. 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.

17. 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.

18. 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.

19. Thank You..